PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Product Description
The KX023 is a tri-axis +/-2g, +/-4g or +/-8g silicon
micromachined accelerometer with integrated 256 byte buffer,
orientation, tap/double tap, and activity detecting algorithms. The
sense element is fabricated using Kionix’s proprietary plasma
micromachining process technology. Acceleration sensing is
based on the principle of a differential capacitance arising from
acceleration-induced motion of the sense element, which further
utilizes common mode cancellation to decrease errors from
process variation, temperature, and environmental stress. The
sense element is hermetically sealed at the wafer level by
bonding a second silicon lid wafer to the device using a glass frit.
A separate ASIC device packaged with the sense element
provides signal conditioning, and intelligent user-programmable
application algorithms. The accelerometer is delivered in a 3 x 3
x 0.9 mm LGA plastic package operating from a 1.8 – 3.6V DC supply. Voltage regulators are used to
maintain constant internal operating voltages over the range of input supply voltages. This results in
stable operating characteristics over the range of input supply voltages and virtually undetectable
ratiometric error. I2C or SPI digital protocol is used to communicate with the chip to configure and
check for updates to the orientation, Directional TapTM detection and activity monitoring algorithms.
Features
3 x 3 x 0.9 mm LGA
User-selectable g Range and Output Data Rate
User-selectable low power mode or high resolution mode
Digital High-Pass Filter Outputs
Embedded FIFO/FILO buffer
Low Power Consumption with FlexSet™ Performance Optimization
Internal voltage regulator
Enhanced integrated Directional Tap/Double-TapTM, and Device-orientation Algorithms
User-configurable wake-up function
Digital I2C up to 3.4 MHz
Digital 3-wire and 4-wire SPI up to 10 MHz
Lead-free Solderability
Excellent Temperature Performance
High Shock Survivability
Factory Programmed Offset and Sensitivity
Self-test Function
36 Thornwood Dr. – Ithaca, NY 14850
tel: 607-257-1080 – fax:607-257-1146
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© 2015 Kionix – All Rights Reserved
Page 1 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Table of Contents
PRODUCT DESCRIPTION ....................................................................................................................................................................1
FEATURES .........................................................................................................................................................................................1
TABLE OF CONTENTS .........................................................................................................................................................................2
FUNCTIONAL DIAGRAM ....................................................................................................................................................................5
PRODUCT SPECIFICATIONS................................................................................................................................................................6
TABLE 1. MECHANICAL .............................................................................................................................................................................. 6
TABLE 2. ELECTRICAL ................................................................................................................................................................................. 7
Start Up Time Profile ........................................................................................................................................................................ 8
Current Profile .................................................................................................................................................................................. 8
Power-On Procedure......................................................................................................................................................................... 9
TABLE 4. ENVIRONMENTAL ....................................................................................................................................................................... 11
TERMINOLOGY ........................................................................................................................................................................................ 12
FUNCTIONALITY ....................................................................................................................................................................................... 13
APPLICATION SCHEMATIC .......................................................................................................................................................................... 14
TABLE 5. KX023 PIN DESCRIPTIONS ........................................................................................................................................................... 14
TEST SPECIFICATIONS ................................................................................................................................................................................ 15
TABLE 6. TEST SPECIFICATIONS .................................................................................................................................................................. 15
PACKAGE DIMENSIONS AND ORIENTATION ................................................................................................................................................... 16
DIMENSIONS ........................................................................................................................................................................................... 16
ORIENTATION.......................................................................................................................................................................................... 17
KX023 DIGITAL INTERFACE .............................................................................................................................................................. 19
2
I C SERIAL INTERFACE ............................................................................................................................................................................... 19
2
I C OPERATION ....................................................................................................................................................................................... 20
WRITING TO A KX023 8-BIT REGISTER ........................................................................................................................................................ 21
READING FROM A KX023 8-BIT REGISTER .................................................................................................................................................... 21
DATA TRANSFER SEQUENCES ..................................................................................................................................................................... 22
HS-MODE .............................................................................................................................................................................................. 23
2
I C TIMING DIAGRAM............................................................................................................................................................................... 24
SPI COMMUNICATIONS............................................................................................................................................................................. 25
4-WIRE SPI INTERFACE............................................................................................................................................................................. 25
4-WIRE SPI TIMING DIAGRAM................................................................................................................................................................... 26
READ AND WRITE REGISTERS ..................................................................................................................................................................... 27
3-WIRE SPI INTERFACE............................................................................................................................................................................. 28
3-WIRE SPI TIMING DIAGRAM................................................................................................................................................................... 29
READ AND WRITE REGISTERS ..................................................................................................................................................................... 30
KX023 EMBEDDED REGISTERS ......................................................................................................................................................... 31
ACCELEROMETER OUTPUTS........................................................................................................................................................................ 33
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tel: 607-257-1080 – fax:607-257-1146
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© 2015 Kionix – All Rights Reserved
Page 2 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
XHP_L .................................................................................................................................................................................................. 34
XHP_H ................................................................................................................................................................................................. 34
YHP_L .................................................................................................................................................................................................. 34
YHP_H ................................................................................................................................................................................................. 34
ZHP_L .................................................................................................................................................................................................. 35
ZHP_H ................................................................................................................................................................................................. 35
XOUT_L ............................................................................................................................................................................................... 35
XOUT_H............................................................................................................................................................................................... 35
YOUT_L ............................................................................................................................................................................................... 36
YOUT_H ............................................................................................................................................................................................... 36
ZOUT_L................................................................................................................................................................................................ 36
ZOUT_H ............................................................................................................................................................................................... 36
COTR ................................................................................................................................................................................................... 37
WHO_AM_I ......................................................................................................................................................................................... 37
TSCP .................................................................................................................................................................................................... 37
TSPP .................................................................................................................................................................................................... 38
INS1 ..................................................................................................................................................................................................... 38
INS2 ..................................................................................................................................................................................................... 39
INS3 ..................................................................................................................................................................................................... 40
STATUS_REG ....................................................................................................................................................................................... 40
INT_REL ............................................................................................................................................................................................... 41
CNTL1 .................................................................................................................................................................................................. 41
CNTL2 .................................................................................................................................................................................................. 42
CNTL3 .................................................................................................................................................................................................. 43
ODCNTL ............................................................................................................................................................................................... 45
INC1 .................................................................................................................................................................................................... 46
INC2 .................................................................................................................................................................................................... 46
INC3 .................................................................................................................................................................................................... 47
INC4 .................................................................................................................................................................................................... 47
INC5 .................................................................................................................................................................................................... 48
INC6 .................................................................................................................................................................................................... 48
TILT_TIMER ......................................................................................................................................................................................... 49
WUFC .................................................................................................................................................................................................. 49
TDTRC.................................................................................................................................................................................................. 49
TDTC .................................................................................................................................................................................................... 50
TTH ...................................................................................................................................................................................................... 50
TTL ....................................................................................................................................................................................................... 51
FTD ...................................................................................................................................................................................................... 51
STD ...................................................................................................................................................................................................... 51
TLT ....................................................................................................................................................................................................... 52
TWS ..................................................................................................................................................................................................... 52
ATH ..................................................................................................................................................................................................... 53
TILT_ANGLE_LL ................................................................................................................................................................................... 53
TILT_ANGLE_HL................................................................................................................................................................................... 53
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tel: 607-257-1080 – fax:607-257-1146
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Page 3 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
HYST_SET ............................................................................................................................................................................................ 54
LP_CNTL .............................................................................................................................................................................................. 54
BUF_CNTL1 ......................................................................................................................................................................................... 55
BUF_CNTL2 ......................................................................................................................................................................................... 56
BUF_STATUS_1 ................................................................................................................................................................................... 57
BUF_STATUS_2 ................................................................................................................................................................................... 57
BUF_CLEAR ......................................................................................................................................................................................... 57
BUF_READ ........................................................................................................................................................................................... 57
SELF_TEST ........................................................................................................................................................................................... 58
KX023 EMBEDDED APPLICATIONS................................................................................................................................................... 59
ORIENTATION DETECTION FEATURE ............................................................................................................................................................. 59
Hysteresis........................................................................................................................................................................................ 59
Device Orientation Angle (aka Tilt Angle)....................................................................................................................................... 60
MOTION INTERRUPT FEATURE DESCRIPTION ................................................................................................................................................. 62
DIRECTIONAL TAP DETECTION FEATURE DESCRIPTION ..................................................................................................................................... 64
Performance Index.......................................................................................................................................................................... 64
Single Tap Detection ....................................................................................................................................................................... 65
Double Tap Detection ..................................................................................................................................................................... 66
SAMPLE BUFFER FEATURE DESCRIPTION ....................................................................................................................................................... 67
FIFO Mode ...................................................................................................................................................................................... 67
Stream Mode .................................................................................................................................................................................. 67
Trigger Mode .................................................................................................................................................................................. 68
FILO Mode ...................................................................................................................................................................................... 68
Buffer Operation ............................................................................................................................................................................. 68
REVISION HISTORY .......................................................................................................................................................................... 74
36 Thornwood Dr. – Ithaca, NY 14850
tel: 607-257-1080 – fax:607-257-1146
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Page 4 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Functional Diagram
X
Accel
Y
Accel
Amplifier
ADC
Z
Accel
DSP
FIFO buffer
I 2 C/SPI Interface
Power
Vdd
GND IO Vdd
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nCS
SDO SDA
SCL ADDR
TRIG INT1 INT2
© 2015 Kionix – All Rights Reserved
Page 5 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Product Specifications
Table 1. Mechanical
(specifications are for operation at 2.5V and T = RT = 25°C unless stated otherwise)
Parameters
Units
Min
Operating Temperature Range
ºC
-40
-
85
Zero-g Offset
mg
±25
±90
mg/ºC
0.2
Zero-g Offset Variation from RT over Temp.
GSEL1=0, GSEL0=0 (± 2g)
1
Sensitivity
16384
17203
7782
8192
8602
GSEL1=1, GSEL0=0 (± 8g)
3891
4096
4301
GSEL1=0, GSEL0=0 (± 2g)
61
64
67
30
32
34
15
16
17
GSEL1=0, GSEL0=1 (± 4g)
counts/g
%/ºC
Self Test Output change on Activiation
Mechanical Resonance (-3dB)
g
3
Non-Linearity
Cross Axis Sensitivity
Noise (RMS at 50Hz with low-pass filter = ODR/9)
1.
2.
3.
4.
counts/g
GSEL1=1, GSEL0=0 (± 8g)
Sensitivity Variation from RT over Temp.
Notes:
Max
15565
GSEL1=0, GSEL0=1 (± 4g)
Sensitivity
1,2
(Buffer 8-bit mode)
Typical
4
0.01
0.35
0.5
Hz
3500 (xy)
1800 (z)
% of FS
0.6
%
2
mg
0.75
0.65
2
Resolution and acceleration ranges are user selectable via I C or SPI.
Sensitivity is proportional to BRES in BUF_CNTRL2.
Resonance as defined by the dampened mechanical sensor.
Noise varies with Output Data Rate (ODR) and Current Consumption settings. Contact
Kionix Engineering for additional details on FlexSet™ Performance Optimization.
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© 2015 Kionix – All Rights Reserved
Page 6 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Table 2. Electrical
(specifications are for operation at 2.5V and T = 25C unless stated otherwise)
Parameters
Units
Min
Typical
Max
Supply Voltage (Vdd) Operating
V
1.71
2.5
3.6
I/O Pads Supply Voltage (VIO)
V
1.7
High Resolution Mode (RES = 1)
Current
Consumption
1
Low Power Mode (RES = 0)
A
10
Standby
0.9
2
V
2
Output Low Voltage (Vio > 2V)
Output High Voltage
Input Low Voltage
Input High Voltage
Output Low Voltage (Vio < 2V)
3
Power Up Time
-
-
0.2 * Vio
V
-
-
0.4
V
0.8 * Vio
-
-
V
-
-
0.2 * Vio
V
0.8 * Vio
-
-
A
Input Pull-down Current
Start Up Time
ms
4
I C Communication Rate
MHz
SPI Communication Rate
MHz
Output Data Rate (ODR)
Bandwidth (-3dB)
0
2.0
ms
2
6
5
Vdd
145
Hz
650
10
3.4
10
0.781
50
RES = 0
Hz
800
RES = 1
Hz
ODR/2
1600
Notes:
1. Current varies with Output Data Rate (ODR) as shown the the chart below, and with
Noise level settings. Contact Kionix Engineering for additional details on FlexSet™
Performance Optimization.
2
2. For I C communication, this assumes a minimum 1.5k pull-up resistor on SCL and
SDA pins.
3. Start up time is from PC1 set to valid outputs. Time varies with Output Data Rate
(ODR); see chart below
4. Power up time is from Vdd valid to device boot completion.
2
5. User selectable through I C or SPI.
6. User selectable and dependent on ODR and RES.
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tel: 607-257-1080 – fax:607-257-1146
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© 2015 Kionix – All Rights Reserved
Page 7 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Start Up Time Profile
KX023 Start Up Time (ms)
100.0
Start Up Time (ms)
KX023 Start Up Time
ODR
Time
(Hz)
(ms)
1600
3.0
800
3.0
400
4.4
200
7.0
100
12
50
22
25
40
12.5
81
81
40
22
12
10.0
7.0
4.4
3
3.0
1.0
1
10
100
1000
10000
ODR (Hz)
Current Profile
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1000
146 146 146
146
100
43
21
13
10
7
5
RES = 0
RES = 1 when >= 200Hz ODR
3.0
2.2
100000.0
Accelerometer ODR [Hz]
10000.0
1000.0
100.0
10.0
1.0
1.8 2.0
1
0.1
Current [uA]
KX023 Representative Current Profile
ODR (Hz)
RES
Current (uA)
0
Standby
0.9
0.781
0
1.8
1.563
0
2.0
3.125
0
2.2
6.25
0
3.0
12.5
0
5
25
0
7
50
0
13
100
0
21
200
0
43
400
1
146
800
1
146
1600
1
146
25600
1
146
KX023 Representative Current (uA)
16x Averaging Filter (default)
© 2015 Kionix – All Rights Reserved
Page 8 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Power-On Procedure
Proper functioning of power-on reset (POR) is dependent on the specific VDDLow and TVdd_Off profile of
individual applications. It is recommended to minimize VDDLow and maximize TVdd_Off. To assure
proper POR in all environmental conditions the application should be evaluated over the range of
VDDLow, TVdd_Off and temperature as POR performance can vary depending on these parameters. It is
also advised that the Vdd ramp up / ramp down TVdd be monotonic. Note that the outputs will not be
stable until Vdd has reached its final value.
Bench Testing has demonstrated POR performance regions for a proper POR trigger. To assure POR
trigger properly executes, setting operational thresholds consistent with Table 3 below is suggested.
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Page 9 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Table 3. POR Performance
Parameters
VDD rise time : TVdd
IOVDD rise time : TIOVdd
Delay from VDD on ramp to a start of IOVDD:
TVdd_IOVDD
VDD off time : TVdd_Off
IOVDD off time : TIOVdd_Off
VDD low voltage : VDDLow
IOVDD low voltage : IOVDDLow
Units
ms
ms
Min
ms
0
ms
ms
mV
mV
10
Typical
Max
10
10
10
250
250
Notes:
1. VDD and IOVDD must always be monotonic ramps without ambiguous state
2. TVdd and TIOVdd rise from 10% to 90% of final value needs to be ≤ 10ms.
3. IOVDD amplitude must remain ≤ VDD amplitude and TVdd_IOVdd ≥ 0ms.
4. In order to prevent the accelerometer from entering an ambiguous state, both VDD and
IOVDD need to be pulled down to GND (≤ 250mV) for a duration of time ≥ 10ms.
It is important the user determines the timing (TVdd_Off) and threshold (VDDLow) levels by evaluating the
performance in the specific system for which the device will be incorporated.
The data provided by Kionix is intended for initial customer design guidance only. Kionix POR testing
looks at a finite number of test configurations. Each customer application will have varying input
sensor parameters (electrical, mechanical, and environmental) that will be different than the
configurations tested by Kionix. Each customer utilizing the sensor will need to properly validate the
sensor (including POR function) within their application under their specific use cases to ensure it
responds as required.
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© 2015 Kionix – All Rights Reserved
Page 10 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Table 4. Environmental
Parameters
Units
Min
Typical
Max
V
-0.5
-
3.63
Operating Temperature Range
ºC
-40
-
85
Storage Temperature Range
ºC
-55
-
150
Mech. Shock (powered and unpowered)
g
-
-
5000 for 0.5ms
10000 for 0.2ms
ESD
V
-
-
2000
Supply Voltage (Vdd)
Absolute Limits
HBM
Caution: ESD Sensitive and Mechanical Shock Sensitive Component, improper handling
can cause permanent damage to the device.
This product conforms to Directive 2002/95/EC of the European Parliament and of the
Council of the European Union (RoHS). Specifically, this product does not contain lead,
mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), or
polybrominated diphenyl ethers (PBDE) above the maximum concentration values (MCV) by
weight in any of its homogenous materials. Homogenous materials are "of uniform
composition throughout."
HF
This product is halogen-free per IEC 61249-2-21. Specifically, the materials used in this
product contain a maximum total halogen content of 1500 ppm with less than 900-ppm
bromine and less than 900-ppm chlorine.
Soldering
Soldering recommendations are available upon request or from www.kionix.com.
36 Thornwood Dr. – Ithaca, NY 14850
tel: 607-257-1080 – fax:607-257-1146
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© 2015 Kionix – All Rights Reserved
Page 11 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Terminology
g
A unit of acceleration equal to the acceleration of gravity at the earth's surface.
m
1g 9.8 2
s
One thousandth of a g (0.0098 m/ s2) is referred to as 1 milli-g (1 mg).
Sensitivity
The sensitivity of an accelerometer is the change in output per unit of input acceleration at nominal Vdd
and temperature. The term is essentially the gain of the sensor expressed in counts per g (counts/g) or
LSB’s per g (LSB/g). Occasionally, sensitivity is expressed as a resolution, i.e. milli-g per LSB
(mg/LSB) or milli-g per count (mg/count). Sensitivity for a given axis is determined by measurements of
the formula:
Sensitivit y
Output @ 1g Output @ 1g
2g
The sensitivity tolerance describes the range of sensitivities that can be expected from a large
population of sensors at room temperature and over life. When the temperature deviates from room
temperature (25ºC), the sensitivity will vary by the amount shown in Table 1.
Zero-g offset
Zero-g offset or 0-g offset describes the actual output of the accelerometer when no acceleration is
applied. Ideally, the output would always be in the middle of the dynamic range of the sensor (content
of the OUTX, OUTY, OUTZ registers = 00h, expressed as a 2’s complement number). However,
because of mismatches in the sensor, calibration errors, and mechanical stress, the output can deviate
from 00h. This deviation from the ideal value is called 0-g offset. The zero-g offset tolerance describes
the range of 0-g offsets of a population of sensors over the operating temperature range.
Self-test
Self-test allows a functional test of the sensor without applying a physical acceleration to it. When
activated, an electrostatic force is applied to the sensor, simulating an input acceleration. The sensor
outputs respond accordingly. If the output signals change within the amplitude specified in Table 1,
then the sensor is working properly and the parameters of the interface chip are within the defined
specifications.
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Page 12 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Functionality
Sense element
The sense element is fabricated using Kionix’s proprietary plasma micromachining process technology.
This process technology allows Kionix to create mechanical silicon structures which are essentially
mass-spring systems that move in the direction of the applied acceleration. Acceleration sensing is
based on the principle of a differential capacitance arising from the acceleration-induced motion.
Capacitive plates on the moving mass move relative to fixed capacitive plates anchored to the
substrate. The sense element is hermetically sealed at the wafer level by bonding a second silicon lid
wafer to the device using a glass frit.
ASIC interface
A separate ASIC device packaged with the sense element provides all of the signal conditioning and
communication with the sensor. The complete measurement chain is composed by a low-noise
capacitance to voltage amplifier which converts the differential capacitance of the MEMS sensor into
an analog voltage that is sent through an analog-to-digital converter. The acceleration data may be
accessed through the I2C digital communications provided by the ASIC. In addition, the ASIC contains
all of the logic to allow the user to choose data rates, g-ranges, filter settings, and interrupt logic. Plus,
there are two programmable state machines which allow the user to create unique embedded functions
based on changes in acceleration.
Factory calibration
Kionix trims the offset and sensitivity of each accelerometer by adjusting gain (sensitivity) and 0-g
offset trim codes stored in non volatile memory (OTP). Additionally, all functional register default
values are also programmed into the non volatile memory. Every time the device is turned on or a
software reset command is issued, the trimming parameters and default register values are
downloaded into the volatile registers to be used during active operation. This allows the device to
function without further calibration.
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Page 13 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Application Schematic
Table 5. KX023 Pin Descriptions
Pin
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
IO Vdd
NC
NC
SCLK/SCL
GND
SDI/SDA
SDO/ADDR
nCS
INT2
NC
INT1
GND
TRIG
Vdd
NC
NC
Description
The power supply input for the digital communication bus. Optionally decouple this pin to ground with a 0.1uF ceramic capacitor.
Not Internally Connected – Can be connected to Vdd, IO Vdd, GND or Float
Not Internally Connected – Can be connected to Vdd, IO Vdd, GND or Float
SPI and I2C Serial Clock
Ground
SPI Data input / I2C Serial Data
Serial Data Out pin during 4 wire SPI communication and part of the device address during I2C communication.
SPI enable / I2C mode select (0 = SPI enabled, I2C communication disabled / 1 = SPI disabled, I2C communication enabled)
Physical Interrupt 2
Not Internally Connected – Can be connected to Vdd, IO Vdd, GND or Float
Physical Interrupt 1
Ground
Trigger pin for FIFO buffer control – Connect to GND when not using external trigger option
The power supply input. Decouple this pin to ground with a 0.1uF ceramic capacitor.
Not Internally Connected – Can be connected to Vdd, IO Vdd, GND or Float
Not Internally Connected – Can be connected to Vdd, IO Vdd, GND or Float
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Page 14 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Test Specifications
! Special Characteristics:
These characteristics have been identified as being critical to the customer. Every part is tested to
verify its conformance to specification prior to shipment.
Table 6. Test Specifications
Parameter
Specification
Test Conditions
Zero-g Offset @ RT1 (2g range) 0 +/- 1475 counts
25°C, Vdd = 2.5 V
Sensitivity @ RT1
(2g range) 16384 +/- 819 counts/g 25°C, Vdd = 2.5 V
1. Room Temperature = 25°C
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Page 15 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Package Dimensions and Orientation
Dimensions
3 x 3 x 0.9 mm LGA
All dimensions and tolerances conform to ASME Y14.5M-1994
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Orientation
Pin 1
+X
+Z
+Y
When device is accelerated in +X, +Y or +Z direction, the corresponding output will increase.
Static X/Y/Z Output Response versus Orientation to Earth’s surface (1g):
GSEL1=0, GSEL0=0 (± 2g)
Position
1
2
3
4
5
6
Top
Bottom
Diagram
Resolution (bits)
X (counts)
Y (counts)
Z (counts)
X-Polarity
Y-Polarity
Z-Polarity
Bottom
16
8
16
8
16
8
16
8
16
0
0 16384 64
0
0 -16384 -64
0
-16384 -64
0
0 16384 64
0
0
0
0
0
0
0
0
0
0
0 16384
0
0
0
+
0
0
+
0
0
0
0
0
0
+
Top
8
16
8
0
0
0
0
0
0
64 -16384 -64
0
0
-
(1g)
Earth’s Surface
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Static X/Y/Z Output Response versus Orientation to Earth’s surface (1g):
GSEL1=0, GSEL0=1 (± 4g)
Position
1
2
3
4
Diagram
Resolution (bits)
X (counts)
Y (counts)
Z (counts)
16
0
-8192
0
8
0
-32
0
0
0
X-Polarity
Y-Polarity
Z-Polarity
16
-8192
0
0
8
-32
0
0
0
0
16
8
0
0
8192 32
0
0
0
0
+
0
16
8192
0
0
8
32
0
0
+
0
0
5
Top
6
Bottom
Bottom
Top
16
8
0
0
0
0
8192 32
16
0
0
-8192
0
0
+
8
0
0
-32
0
0
-
(1g)
Earth’s Surface
Static X/Y/Z Output Response versus Orientation to Earth’s surface (1g):
GSEL1=1, GSEL0=0 (± 8g)
Position
1
2
3
4
Diagram
Resolution (bits)
X (counts)
Y (counts)
Z (counts)
X-Polarity
Y-Polarity
Z-Polarity
16
0
-4096
0
0
0
8
0
-16
0
16
-4096
0
0
0
0
8
-16
0
0
16
8
0
0
4096 16
0
0
0
0
+
0
(1g)
16
4096
0
0
+
0
0
8
16
0
0
5
Top
6
Bottom
Bottom
Top
16
8
0
0
0
0
4096 16
0
0
+
16
0
0
-4096
8
0
0
-16
0
0
-
Earth’s Surface
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
KX023 Digital Interface
The Kionix KX023 digital accelerometer has the ability to communicate via the I2C and SPI digital serial
interface protocols. This allows for easy system integration by eliminating analog-to-digital converter
requirements and by providing direct communication with system micro-controllers.
The serial interface terms and descriptions as indicated in Table 7 below will be observed throughout this
document.
Term
Transmitter
Receiver
Master
Slave
Description
The device that transmits data to the bus.
The device that receives data from the bus.
The device that initiates a transfer, generates clock signals, and terminates a transfer.
The device addressed by the Master.
Table 7. Serial Interface Terminologies
I2C Serial Interface
As previously mentioned, the KX023 has the ability to communicate on an I2C bus. I2C is primarily used for
synchronous serial communication between a Master device and one or more Slave devices. The Master,
typically a micro controller, provides the serial clock signal and addresses Slave devices on the bus. The
KX023 always operates as a Slave device during standard Master-Slave I2C operation.
I2C is a two-wire serial interface that contains a Serial Clock (SCL) line and a Serial Data (SDA) line. SCL is a
serial clock that is provided by the Master, but can be held low by any Slave device, putting the Master into a
wait condition. SDA is a bi-directional line used to transmit and receive data to and from the interface. Data is
transmitted MSB (Most Significant Bit) first in 8-bit per byte format, and the number of bytes transmitted per
transfer is unlimited. The I2C bus is considered free when both lines are high.
The I2C interface is compliant with high-speed mode, fast mode and standard mode I2C protocols.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
MCU
SDA
SCL
ADDR
SDA
SCL
ADDR
Figure 1. Multiple KX023 I2C Connection
I2C Address
Address
7 bit
Description
Pad
Address Address
I2C Wr
VDD
1Fh
3Eh
0
0
1
1
1
1
1
0
I2C Rd
VDD
1Fh
3Fh
0
0
1
1
1
1
1
1
I2C Wr
VSS
1Eh
3Ch
0
0
1
1
1
1
0
0
I2C Rd
VSS
1Eh
3Dh
0
0
1
1
1
1
0
1
I2C Operation
Transactions on the I2C bus begin after the Master transmits a start condition (S), which is defined as a highto-low transition on the data line while the SCL line is held high. The bus is considered busy after this
condition. The next byte of data transmitted after the start condition contains the Slave Address (SAD) in the
seven MSBs (Most Significant Bits), and the LSB (Least Significant Bit) tells whether the Master will be
receiving data ‘1’ from the Slave or transmitting data ‘0’ to the Slave. When a Slave Address is sent, each
device on the bus compares the seven MSBs with its internally stored address. If they match, the device
considers itself addressed by the Master. The KX023’s Slave Address is comprised of a programmable part
and a fixed part, which allows for connection of multiple KX023’s to the same I2C bus. The Slave Address
associated with the KX023 is 001111X, where the programmable bit, X, is determined by the assignment of
ADDR (pin 7) to GND or IO_Vdd. Figure 1 above shows how two KX023’s would be implemented on an I2C
bus.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
It is mandatory that receiving devices acknowledge (ACK) each transaction. Therefore, the transmitter must
release the SDA line during this ACK pulse. The receiver then pulls the data line low so that it remains stable
low during the high period of the ACK clock pulse. A receiver that has been addressed, whether it is Master or
Slave, is obliged to generate an ACK after each byte of data has been received. To conclude a transaction,
the Master must transmit a stop condition (P) by transitioning the SDA line from low to high while SCL is high.
The I2C bus is now free. Note that if the KX023 is accessed through I2C protocol before the startup is finished
a NACK signal is sent.
Writing to a KX023 8-bit Register
Upon power up, the Master must write to the KX023’s control registers to set its operational mode. Therefore,
when writing to a control register on the I2C bus, as shown Sequence 1 on the following page, the following
protocol must be observed: After a start condition, SAD+W transmission, and the KX023 ACK has been
returned, an 8-bit Register Address (RA) command is transmitted by the Master. This command is telling the
KX023 to which 8-bit register the Master will be writing the data. Since this is I 2C mode, the MSB of the RA
command should always be zero (0). The KX023 acknowledges the RA and the Master transmits the data to
be stored in the 8-bit register. The KX023 acknowledges that it has received the data and the Master
transmits a stop condition (P) to end the data transfer. The data sent to the KX023 is now stored in the
appropriate register. The KX023 automatically increments the received RA commands and, therefore, multiple
bytes of data can be written to sequential registers after each Slave ACK as shown in Sequence 2 on the
following page. When the auto-increment feature reaches register address 0x7F (Buffer Read), it stops and
does not advance to register address 0x80. A new read command must be issued for registers above 0x7F.
The part then continues to auto-increment until it reaches address 0xFF.
Reading from a KX023 8-bit Register
When reading data from a KX023 8-bit register on the I2C bus, as shown in Sequence 3 on the next page, the
following protocol must be observed: The Master first transmits a start condition (S) and the appropriate Slave
Address (SAD) with the LSB set at ‘0’ to write. The KX023 acknowledges and the Master transmits the 8-bit
RA of the register it wants to read. The KX023 again acknowledges, and the Master transmits a repeated start
condition (Sr). After the repeated start condition, the Master addresses the KX023 with a ‘1’ in the LSB
(SAD+R) to read from the previously selected register. The Slave then acknowledges and transmits the data
from the requested register. The Master does not acknowledge (NACK) it received the transmitted data, but
transmits a stop condition to end the data transfer. Note that the KX023 automatically increments through its
sequential registers, allowing data to be read from multiple registers following a single SAD+R command as
shown below in Sequence 4 on the following page.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Data Transfer Sequences
The following information clearly illustrates the variety of data transfers that can occur on the I 2C bus and how
the Master and Slave interact during these transfers. Table 8 defines the I2C terms used during the data
transfers.
Term
S
Sr
SAD
W
R
ACK
NACK
RA
Data
P
Definition
Start Condition
Repeated Start Condition
Slave Address
Write Bit
Read Bit
Acknowledge
Not Acknowledge
Register Address
Transmitted/Received Data
Stop Condition
Table 8. I2C Terms
Sequence 1. The Master is writing one byte to the Slave.
Master
Slave
S
SAD + W
RA
ACK
DATA
ACK
P
ACK
Sequence 2. The Master is writing multiple bytes to the Slave.
Master
Slave
S
SAD + W
RA
ACK
DATA
ACK
DATA
ACK
P
ACK
Sequence 3. The Master is receiving one byte of data from the Slave.
Master
Slave
S
SAD + W
RA
ACK
Sr
SAD + R
ACK
NACK
ACK
P
DATA
Sequence 4. The Master is receiving multiple bytes of data from the Slave.
Master
Slave
S
SAD + W
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RA
ACK
Sr
ACK
SAD + R
ACK
ACK
DATA
NACK
DATA
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P
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
HS-mode
To enter the 3.4MHz high speed mode of communication, the device must receive the following sequence of
conditions from the master: a Start condition followed by a Master code (00001XXX) and a Master Nonacknowledge. Once recognized, the device switches to HS-mode communication. Read/write data transfers
then proceed as described in the sequences above. Devices return to the FS-mode after a STOP occurrence
on the bus.
Sequence 5. HS-mode data transfer of the Master writing multiple bytes to the Slave.
Speed
Master
Slave
S
FS-mode
M-code NACK
Sr
SAD + W
ACK
HS-mode
RA
ACK
FS-mode
DATA
P
ACK
n bytes + ack.
Sequence 6. HS-mode data transfer of the Master receiving multiple bytes of data from the Slave.
Speed
Master
Slave
S
Speed
Master
Slave
Sr
FS-mode
M-code NACK
Sr
HS-mode
SAD + W
RA
ACK
ACK
HS-mode
FS-mode
SAD + R
NACK
ACK
DATA
ACK
P
DATA
(n-1) bytes +
ack.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
I2C Timing Diagram
t
t0
t2
t1
t3
t4
t6
t5
t7
SCL
bit7
5
SDA
bit6
5
bit0
addr_ack
b7
S
bit7
5
Sr
t8
t9
bit0
5
addr_nack
t11
t10
P
Table 9. I2C Timing (Fast Mode)
Number
Description
MIN
MAX
Units
t0
t1
t2
t3
t4
t5
t6
t7
t8
t9
t10
t11
Note
SDA low to SCL low transition (Start event)
SDA low to first SCL rising edge
SCL pulse width: high
SCL pulse width: low
SCL high before SDA falling edge (Start Repeated)
SCL pulse width: high during a S/Sr/P event
SCL high before SDA rising edge (Stop)
SDA pulse width: high
SDA valid to SCL rising edge
SCL rising edge to SDA invalid
SCL falling edge to SDA valid (when slave is transmitting)
SCL falling edge to SDA invalid (when slave is transmitting)
50
100
100
100
50
100
50
25
50
50
0
2.5
100
-
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
us
Recommended I2C CLK
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
SPI Communications
4-Wire SPI Interface
The KX023 also utilizes an integrated 4-Wire Serial Peripheral Interface (SPI) for digital communication. The
SPI interface is primarily used for synchronous serial communication between one Master device and one or
more Slave devices. The Master, typically a micro controller, provides the SPI clock signal (SCLK) and
determines the state of Chip Select (nCS). The KX023 always operates as a Slave device during standard
Master-Slave SPI operation.
4-wire SPI is a synchronous serial interface that uses two control and two data lines. With respect to the
Master, the Serial Clock output (SCLK), the Data Output (SDI or MOSI) and the Data Input (SDO or MISO) are
shared among the Slave devices. The Master generates an independent Chip Select (nCS) for each Slave
device that goes low at the start of transmission and goes back high at the end. The Slave Data Output (SDO)
line, remains in a high-impedance (hi-z) state when the device is not selected, so it does not interfere with any
active devices. This allows multiple Slave devices to share a master SPI port as shown in Figure 2 below.
KX023
KX023
Figure 2. KX023 4-wire SPI Connections
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
4-Wire SPI Timing Diagram
t3
t
t1
t2
t4
nCS
CLK
SDI
bit 7
bit 6
bit 1
5
bit 0
SDO
bit 7
5
bit 7
5
t5
t6
bit 6
bit 6
bit 1
5
bit 1
5
bit 0
bit 0
t7
Table 10. 4-Wire SPI Timing
Number
t1
t2
t3
t4
t5
t6
t7
Description
CLK pulse width: high
CLK pulse width: low
nCS low to first CLK rising edge
nCS low after the final CLK rising edge
SDI valid to CLK rising edge
CLK rising edge to SDI invalid
CLK falling edge to SDO valid
MIN MAX
40
40
20
30
10
10
35
Units
ns
ns
ns
ns
ns
ns
ns
Notes
1. t7 is only present during reads.
2. Timings are for Vdd of 1.8V to 3.6V with 1K pull-up resistor and maximum 20pF load capacitor
on SDO.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Read and Write Registers
The registers embedded in the KX023 have 8-bit addresses. Upon power up, the Master must write to the
accelerometer’s control registers to set its operational mode. On the falling edge of nCS, a 2-byte command is
written to the appropriate control register. The first byte initiates the write to the appropriate register, and is
followed by the user-defined, data byte. The MSB (Most Significant Bit) of the register address byte will
indicate “0” when writing to the register and “1” when reading from the register. This operation occurs over 16
clock cycles. All commands are sent MSB first, and the host must return nCS high for at least one clock cycle
before the next data request. Figure 3 below shows the timing diagram for carrying out an 8-bit register write
operation.
Write Address
First 8 bits
Second 8 bits
Last 8 bits
CLK
SDI
SDO
A7 A6 A5 A4 A3 A2 A1 A0
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D2
D1
D0
HI-Z
HI-Z
CS
Figure 3. Timing Diagram for 8-Bit Register Write Operation
In order to read an 8-bit register, an 8-bit register address must be written to the accelerometer to initiate the
read. The MSB of this register address byte will indicate “0” when writing to the register and “1” when reading
from the register. Upon receiving the address, the accelerometer returns the 8-bit data stored in the
addressed register. This operation also occurs over 16 clock cycles. All returned data is sent MSB first, and
the host must return nCS high for at least one clock cycle before the next data request. Figure 4 shows the
timing diagram for an 8-bit register read operation.
Read Address
First 8 bits
Second 8 bits
Last 8 bits
CLK
SDI
SDO
A7 A6 A5 A4 A3 A2 A1 A0
HI-Z
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D3 D2
D1
D0
HI-Z
CS
Figure 4. Timing Diagram for 8-Bit Register Read Operation
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
3-Wire SPI Interface
The KX023 also utilizes an integrated 3-Wire Serial Peripheral Interface (SPI) for digital communication. 3wire SPI is a synchronous serial interface that uses two control lines and one data line. With respect to the
Master, the Serial Clock output (SCLK), the Data Output/Input (SDI) are shared among the Slave devices.
The Master generates an independent Chip Select (nCS) for each Slave device that goes low at the start of
transmission and goes back high at the end. This allows multiple Slave devices to share a master SPI port as
shown in Figure 5 below.
KX023
KX023
Figure 5. KX023 3-wire SPI Connections
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
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KX023-1025
Rev. 10.0
Apr-2015
3-Wire SPI Timing Diagram
t3
t1
t2
t4
nCS
CLK
SDI
bit 7
bit 6
t5
bit 1
5
bit 0
bit 7
t7
t6
bit 1
5
bit 0
MIN
40
40
20
20
10
10
tbd
-
MAX
35
t8
Table 11. 3-Wire SPI Timing
Number
t1
t2
t3
t4
t5
t6
t7
t8
Description
CLK pulse width: high
CLK pulse width: low
nCS low to first CLK rising edge
nCS low after the final CLK falling edge
SDI valid to CLK rising edge
CLK rising edge to SDI input invalid
CLK extra clock cycle rising edge to SDI output
becomes
CLK
fallingvalid
edge to SDI output becomes valid
Units
ns
ns
ns
ns
ns
ns
ns
ns
Notes
1. t7 and t8 are only present during reads.
2. Timings are for Vdd of 1.8V to 3.6V with 1K pull-up resistor and maximum 20pF
load capacitor on SDI.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Read and Write Registers
The registers embedded in the KX023 have 8-bit addresses. Upon power up, the Master must write to the
accelerometer’s control registers to set its operational mode. On the falling edge of nCS, a 2-byte command is
written to the appropriate control register. The first byte initiates the write to the appropriate register, and is
followed by the user-defined, data byte. The MSB (Most Significant Bit) of the register address byte will
indicate “0” when writing to the register and “1” when reading from the register. A read operation occurs over
17 clock cycles and a write operation occurs over 16 clock cycles. All commands are sent MSB first, and the
host must return nCS high for at least one clock cycle before the next address transmission. Figure 6 below
shows the timing diagram for carrying out an 8-bit register write operation.
SCLK
SDI
A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
(MSB)
(MSB)
CS
Figure 6. Timing Diagram for 8-Bit Register Write Operation
In order to read an 8-bit register, an 8-bit register address must be written to the accelerometer to initiate the
read. The MSB of this register address byte will indicate “0” when writing to the register and “1” when reading
from the register. Upon receiving the address, the accelerometer returns the 8-bit data stored in the
addressed register. For 3-wire read operations, one extra clock cycle between the address byte and the data
output byte is required. Therefore, this operation occurs over 17 clock cycles. All returned data is sent MSB
first, and the host must return nCS high for at least one clock cycle before the next data request. Figure 7
shows the timing diagram for an 8-bit register read operation.
SCLK
SDI
D7 D6 D5 D4 D3 D2 D1 D0 HI-Z
A7 A6 A5 A4 A3 A2 A1 A0
(MSB)
(MSB)
CS
Figure 7. Timing Diagram for 8-Bit Register Read Operation
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
KX023 Embedded Registers
The KX023 has 57 embedded 8-bit registers that are accessible by the user. This section contains the
addresses for all embedded registers and also describes bit functions of each register. Table 12 below
provides a listing of the accessible 8-bit registers and their addresses.
Address
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
20h
21h
22h
23h
24h
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Register Name
XHPL
XHPH
YHPL
YHPH
ZHPL
ZHPH
XOUTL
XOUTH
YOUTL
YOUTH
ZOUTL
ZOUTH
COTR
Kionix Reserved
Kionix Reserved
Who_AM_I
TSCP
TSPP
INS1
INS2
INS3
STAT
Kionix Reserved
INT_REL
CNTL1*
CNTL2*
CNTL3*
ODCNTL*
INC1*
INC2*
INC3*
INC4*
INC5*
INC6*
TILT_TIMER*
WUFC*
TDTRC*
R/W
R
R
R
R
R
R
R
R
R
R
R
R
R
R/W
R
R
R
R
R
R
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
25h
26h
27h
28h
29h
2Ah
2Bh
2Ch
2Dh
2Eh
2Fh
30h
31h
32h
33h
34h
35h
36h
37h
38h
39h
3Ah
3Bh
3Ch
3Dh
3Eh
3Fh
60h
TDTC*
TTH*
TTL*
FTD*
STD*
TLT*
TWS*
Kionix Reserved
Kionix Reserved
Kionix Reserved
Kionix Reserved
ATH*
Kionix Reserved
TILT_ANGLE_LL*
TILT_ANGLE_HL*
HYST_SET*
LP_CNTL*
Kionix Reserved
Kionix Reserved
Kionix Reserved
Kionix Reserved
BUF_CNTL1*
BUF_CNTL2*
BUF_STATUS_1
BUF_STATUS_2
BUF_CLEAR
BUF_READ
SELF_TEST
KX023-1025
Rev. 10.0
Apr-2015
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
R
W
R
R/W
* Note: - When changing the contents of these registers, the PC1 bit in CTRL_REG1 must first be set to “0”.
- Reserved registers should not be written.
Table 12. KX023 Register Map
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Page 32 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
KX023 Register Descriptions
Accelerometer Outputs
These registers contain up to 16-bits of valid acceleration data for each axis. Depending on the setting
of the RES bit in CTRL_REG1, the user may choose to read only the 8 MSB thus reading an effective
8-bit resolution. When BRES = ‘0’ in BUF_CNTL2 the 8 MSB is the only data recorded in the buffer.
The data is updated every user-defined ODR period, is protected from overwrite during each read, and
can be converted from digital counts to acceleration (g) per Table 13 below. The register acceleration
output binary data is represented in 2’s complement format. For example, if N = 16 bits, then the
Counts range is from -32768 to 32767, and if N = 8 bits, then the Counts range is from -128 to 127.
16-bit
Register Data
(2’s complement)
Equivalent
Counts in
decimal
Range = +/-2g
Range = +/-4g
Range = +/-8g
0111 1111 1111 1111
32767
+2.0000g
+3.9999g
+7.9998g
0111 1111 1111 1110
32766
+1.9999g
+3.9998g
+7.9995g
…
…
…
…
…
0000 0000 0001
1
+0.00006g
+0.0001g
+0.0002g
0000 0000 0000
0
0.000g
0.000g
0.000g
1111 1111 1111 1111
-1
-0.00006g
-0.0001g
-0.0002g
…
…
…
…
…
1000 0000 0000 0001
-32767
-1.9999g
-3.9999g
-7.9998g
1000 0000 0000 0000
-32768
-2.0000g
-4.000g
-8.000g
8-bit
Register Data
(2’s complement)
Equivalent
Counts in
decimal
Range = +/-2g
Range = +/-4g
Range = +/-8g
0111 1111
127
+1.984g
+3.968g
+7.936g
0111 1110
126
+1.968g
+3.936g
+7.872g
…
…
…
…
…
0000 0001
1
+0.016g
+0.032g
+0.064g
0000 0000
0
0.000g
0.000g
0.000g
1111 1111
-1
-0.016g
-0.032g
-0.064g
…
…
…
…
…
1000 0001
-127
-1.984g
-3.968g
-7.936g
1000 0000
-128
-2.000g
-4.000g
-8.000g
Table 13. Acceleration (g) Calculation
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Page 33 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
XHP_L
X-axis high pass filter accelerometer output least significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
XHPD7
Bit7
R
XHPD6
Bit6
R
XHPD5
Bit5
R
XHPD4
Bit4
R
XHPD3
Bit3
R
XHPD2
Bit2
R
R
XHPD1
XHPD0
Bit1
Bit0
2
I C Address: 0x00h
XHP_H
X-axis high pass filter accelerometer output most significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
XHPD15
Bit7
R
XHPD14
Bit6
R
XHPD13
Bit5
R
XHPD12
Bit4
R
XHPD11
Bit3
R
XHPD10
Bit2
R
R
XHPD9
XHPD8
Bit1
Bit0
2
I C Address: 0x01h
YHP_L
Y-axis high pass filter accelerometer output least significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
YHPD7
Bit7
R
YHPD6
Bit6
R
YHPD5
Bit5
R
YHPD4
Bit4
R
YHPD3
Bit3
R
YHPD2
Bit2
R
R
YHPD1
YHPD0
Bit1
Bit0
2
I C Address: 0x02h
YHP_H
Y-axis high pass filter accelerometer output most significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
YHPD15
Bit7
R
YHPD14
Bit6
R
YHPD13
Bit5
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R
YHPD12
Bit4
R
YHPD11
Bit3
R
YHPD10
Bit2
R
R
YHPD9
YHPD8
Bit1
Bit0
2
I C Address: 0x03h
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Page 34 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
ZHP_L
Z-axis high pass filter accelerometer output least significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
ZHPD7
Bit7
R
ZHPD6
Bit6
R
ZHPD5
Bit5
R
ZHPD4
Bit4
R
ZHPD3
Bit3
R
ZHPD2
Bit2
R
R
ZHPD1
ZHPD0
Bit1
Bit0
2
I C Address: 0x04h
ZHP_H
Z-axis high pass filter accelerometer output most significant byte. Data is updated at the ODR
frequency determined by OWUF in CNTL3.
R
ZHPD15
Bit7
R
ZHPD14
Bit6
R
ZHPD13
Bit5
R
ZHPD12
Bit4
R
ZHPD11
Bit3
R
ZHPD10
Bit2
R
R
ZHPD9
ZHPD8
Bit1
Bit0
2
I C Address: 0x05h
XOUT_L
X-axis accelerometer output least significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
XOUTD7
Bit7
R
XOUTD6
Bit6
R
XOUTD5
Bit5
R
XOUTD4
Bit4
R
XOUTD3
Bit3
R
R
R
XOUTD2 XOUTD1 XOUTD0
Bit2
Bit1
Bit0
2
I C Address: 0x06h
XOUT_H
X-axis accelerometer output most significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
R
R
R
R
R
R
R
XOUTD15 XOUTD14 XOUTD13 XOUTD12 XOUTD11 XOUTD10 XOUTD9 XOUTD8
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
2
I C Address: 0x07h
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Page 35 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
YOUT_L
Y-axis accelerometer output least significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
YOUTD7
Bit7
R
YOUTD6
Bit6
R
YOUTD5
Bit5
R
YOUTD4
Bit4
R
YOUTD3
Bit3
R
R
R
YOUTD2 YOUTD1 YOUTD0
Bit2
Bit1
Bit0
2
I C Address: 0x08h
YOUT_H
Y-axis accelerometer output most significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
R
R
R
R
R
R
R
YOUTD15 YOUTD14 YOUTD13 YOUTD12 YOUTD11 YOUTD10 YOUTD9 YOUTD8
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
2
I C Address: 0x09h
ZOUT_L
Z-axis accelerometer output least significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
ZOUTD7
Bit7
R
ZOUTD6
Bit6
R
ZOUTD5
Bit5
R
ZOUTD4
Bit4
R
ZOUTD3
Bit3
R
R
R
ZOUTD2 ZOUTD1 ZOUTD0
Bit2
Bit1
Bit0
2
I C Address: 0x0Ah
ZOUT_H
Z-axis accelerometer output most significant byte. Data is updated at the ODR frequency determined
by OSA in ODCNTL.
R
R
R
R
R
R
R
R
YOUTD15 YOUTD14 YOUTD13 YOUTD12 YOUTD11 YOUTD10 YOUTD9 YOUTD8
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
2
I C Address: 0x0Bh
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Page 36 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
COTR
This register can be used to verify proper integrated circuit functionality. It always has a byte value of
0x55h unless the COTC bit in CNTL2 is set. At that point this value is set to 0xAAh. The byte value is
returned to 0x55h after reading this register and the COTC bit in CNTL2 is cleared.
R
DCSTR7
Bit7
R
DCSTR6
Bit6
R
DCSTR5
Bit5
R
DCSTR4
Bit4
R
DCSTR3
Bit3
R
DCSTR2
Bit2
R
R
DCSTR1 DCSTR0
Bit1
Bit0
2
I C Address: 0x0Ch
Reset Value
01010101
WHO_AM_I
This register can be used for supplier recognition, as it can be factory written to a known byte value.
The default value is 0x15h.
R
WIA7
Bit7
R
WIA6
Bit6
R
WIA5
Bit5
R
WIA4
Bit4
R
WIA3
Bit3
R
WIA2
Bit2
R
R
WIA1
WIA0
Bit1
Bit0
2
I C Address: 0x0Fh
Reset Value
00010101
Tilt Position Registers
These two registers report previous and current position data that is updated at the user-defined ODR
frequency and is protected during register read. Table 14 describes the reported position for each bit
value.
TSCP
Current Tilt Position Register.
R
0
Bit7
R
0
Bit6
R
LE
Bit5
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R
RI
Bit4
R
DO
Bit3
R
UP
Bit2
R
R
FD
FU
Bit1
Bit0
2
I C Address: 0x10h
Reset Value
00100000
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Page 37 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
TSPP
Previous Tilt Positon Register.
R
0
Bit7
R
0
Bit6
R
LE
Bit5
R
RI
Bit4
R
DO
Bit3
Bit
LE
RI
DO
UP
FD
FU
R
UP
Bit2
R
R
FD
FU
Bit1
Bit0
2
I C Address: 0x11h
Reset Value
00100000
Description
Left State (X-)
Right State (X+)
Down State (Y-)
Up State (Y+)
Face-Down State (Z-)
Face-Up State (Z+)
Table 14. KX023 Tilt Position
Interrupt Source Registers
These three registers report interrupt state changes. This data is updated when a new interrupt event
occurs and each application’s result is latched until the interrupt release register is read.
INS1
This register indicates the triggering axis when a tap/double tap interrupt occurs. Data is updated at
the ODR settings determined by OTDT in CNTL3.
R
0
Bit7
R
0
Bit6
R
TLE
Bit5
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R
TRI
Bit4
R
TDO
Bit3
R
TUP
Bit2
R
R
TFD
TFU
Bit1
Bit0
2
I C Address: 0x12h
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Page 38 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
Bit
TLE
TRI
TDO
TUP
TFD
TFU
KX023-1025
Rev. 10.0
Apr-2015
Description
X Negative (X-) Reported
X Positive (X+) Reported
Y Negative (Y-) Reported
Y Positive (Y+) Reported
Z Negative (Z-) Reported
Z Positive (Z+) Reported
Table 15. KX023 Directional TapTM Reporting
INS2
This register tells witch function caused an interrupt.
R
0
Bit7
R
BFI
Bit6
R
WMI
Bit5
R
DRDY
Bit4
R
TDTS1
Bit3
R
TDTS0
Bit2
R
R
WUFS
TPS
Bit1
Bit0
2
I C Address: 0x13h
BFI – indicates buffer full interrupt. Automatically cleared when buffer is read.
BFI = 0 – Buffer is not full
BFI = 1 – Buffer is full
WMI – Watermark interrupt, bit is set to one when FIFO has filled up to the value stored in the
sample bits.This bit is automatically cleared when FIFO/FILO is read and the content
returns to a value below the value stored in the sample bits.
WMI = 0 – Buffer watermark has not been exceeded
WMI = 1 – Buffer watermark has been exceeded
DRDY – indicates that new acceleration data (0x06h to 0x0Bh) is available. This bit is cleared
when acceleration data is read or the interrupt release register INT_REL is read.
DRDY = 0 - new acceleration data not available
DRDY = 1 - new acceleration data available
TDTS(1,0) – status of tap/double tap, bit is released when interrupt release register INT_REL is
read.
TDTS1 TDTS0
Event
0
0
No Tap
0
1
Single Tap
1
0
Double Tap
1
1
Do not exist
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
WUFS – Status of Wake up. This bit is cleared when the interrupt release register INT_REL is
read.
WUFS = 1 – Motion has activated the interrupt
WUFS = 0 – No motion
TPS – Tilt Position status. This bit is cleared when the interrupt release register INT_REL is
read.
TPS = 0 – Position not changed
TPS = 1 – Position changed
INS3
This register reports the axis and direction of detected motion.
R
0
Bit7
R
0
Bit6
R
XNWU
Bit5
R
XPWU
Bit4
R
YNWU
Bit3
Bit
XNWU
XPWU
YNWU
YPWU
ZNWU
ZPWU
R
YPWU
Bit2
R
R
ZNWU
ZPWU
Bit1
Bit0
2
I C Address: 0x14h
Description
X Negative (X-) Reported
X Positive (X+) Reported
Y Negative (Y-) Reported
Y Positive (Y+) Reported
Z Negative (Z-) Reported
Z Positive (Z+) Reported
Table 16. KX023 Motion DetectionTM Reporting
STATUS_REG
This register reports the status of the interrupt.
R
0
Bit7
R
0
Bit6
R
0
Bit5
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R
INT
Bit4
R
0
Bit3
R
0
Bit2
R
R
0
0
Bit1
Bit0
2
I C Address: 0x15h
© 2015 Kionix – All Rights Reserved
Page 40 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
INT reports the combined (OR) interrupt information of all features. When BFI and WMI in
INS2 are 0, the INT bit is released to 0 when INL is read. If WMI or BFI is 1, INT bit
remains at 1 until they are cleared by FIFO/FILO buffer read.
0 = no interrupt event
1 = interrupt event has occurred
INT_REL
Latched interrupt source information (INS1,INS2, INS3 except WMI/BFI and INT when WMI/BFI is
zero) is cleared and physical interrupt latched pin is changed to it’s inactive state when this register is
read. Read value is dummy.
R
X
Bit7
R
X
Bit6
R
X
Bit5
R
X
Bit4
R
X
Bit3
R
X
Bit2
R
R
X
X
Bit1
Bit0
2
I C Address: 0x17h
CNTL1
Read/write control register that controls the main feature set.
R/W
PC1
Bit7
R/W
RES
Bit6
R/W
DRDYE
Bit5
R/W
GSEL1
Bit4
R/W
GSEL0
Bit3
R/W
TDTE
Bit2
R/W
R/W
WUFE
TPE
Bit1
Bit0
2
I C Address: 0x18h
Reset Value
00000000
PC1 controls the operating mode of the KX023. When in RES = 0, please allow 1.2/ODR
delay time when transistioning from stand-by PC1 = 0 to operating mode PC1 = 1 to
allow new settings to load.
0 = stand-by mode
1 = operating mode
RES determines the performance mode of the KX023. The noise varies with ODR, RES and
different LP_CNTL settings possibly reducing the effective resolution. Note that to
change the value of this bit, the PC1 bit must first be set to “0”.
0 = low current.
1 = high current. Bandwidth (Hz) = ODR/2
DRDYE enables the reporting of the availability of new acceleration data as an interrupt. Note
that to change the value of this bit, the PC1 bit must first be set to “0”.
0 = availability of new acceleration data is not reflected as an interrupt
1 = availability of new acceleration data is reflected as an interrupt
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
GSEL1, GSEL0 selects the acceleration range of the accelerometer outputs per Table 17.
Note that to change the value of this bit, the PC1 bit must first be set to “0”.
GSEL1 GSEL0
0
0
0
1
1
0
Range
+/-2g
+/-4g
+/-8g
Table 17. Selected Acceleration Range
TDTE enables the Directional TapTM function that will detect single and double tap events.
Note that to change the value of this bit, the PC1 bit must first be set to “0”.
TDTE = 0 – disable
TDTE = 1 - enable
WUFE enables the Wake Up (motion detect) function. 0= disabled, 1= enabled. Note that to
change the value of this bit, the PC1 bit must first be set to “0”.
0 = Wake Up function disabled
1 = Wake Up function enabled
TPE enables the Tilt Position function that will detect changes in device orientation. Note that
to change the value of this bit, the PC1 bit must first be set to “0”.
TPE = 0 – disable
TPE = 1 - enable
CNTL2
Read/write control register that provides more feature set control. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
SRST
Bit7
R/W
COTC
Bit6
R/W
LEM
Bit5
R/W
RIM
Bit4
R/W
DOM
Bit3
R/W
UPM
Bit2
R/W
R/W
FDM
FUM
Bit1
Bit0
2
I C Address: 0x19h
Reset Value
00111111
SRST initiates software reset, which performs the RAM reboot routine. This bit will remain 1
until the RAM reboot routine is finished.
SRST = 0 – no action
SRST = 1 – start RAM reboot routine
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
COTC Command test control.
DCST = 0 – no action
DCST = 1 – sets STR register to 0xAAh and when STR is read, sets this bit to 0 and
sets STR to 0x55h
TLEM, TRIM, TDOM, TUPM, TFDM these bits control the tilt axis mask. Per Table 18, if a
direction’s bit is set to one (1), tilt in that direction will generate an interrupt. If it is set
to zero (0), tilt in that direction will not generate an interrupt. Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
Bit
TLEM
TRIM
TDOM
TUPM
TFDM
TFUM
Description
X Negative (X-)
X Positive (X+)
Y Negative (Y-)
Y Positive (Y+)
Z Negative (Z-)
Z Positive (Z+)
Table 18. Tilt DirectionTM Axis Mask
CNTL3
Read/write control register that provides more feature set control. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
OTP1
Bit7
R/W
OTP0
Bit6
R/W
OTDT2
Bit5
R/W
OTDT1
Bit4
R/W
OTDT0
Bit3
R/W
OWUF2
Bit2
R/W
R/W
OWUF1
OWUF0
Bit1
Bit0
2
I C Address: 0x1Ah
Reset Value
10011000
OTPA, OTPB sets the output data rate for the Tilt Position function per Table 19. The default
Tilt Position ODR is 12.5Hz.
OTP1
0
0
1
1
OTP0
0
1
0
1
Output Data Rate
1.563Hz
6.25Hz
12.5Hz
50Hz
Table 19. Tilt Position Function Output Data Rate
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
OTDTA, OTDTB sets the output data rate for the Directional TapTM function per Table 20.
The default Directional TapTM ODR is 400Hz.
OTDT2 OTDT1 OTDT0 Output Data Rate
0
0
0
50Hz
0
0
1
100Hz
0
1
0
200Hz
0
1
1
400Hz
1
0
0
12.5Hz
1
0
1
25Hz
1
1
0
800Hz
1
1
1
1600Hz
Table 20. Directional TapTM Function Output Data Rate
OWUF2, OWUF1, OWUF0 sets the output data rate for the general motion detection function
and the high-pass filtered outputs per Table 21. The default Motion Wake Up ODR is
0.781Hz.
OWUF2 OWUF1 OWUF0 Output Data Rate
0
0
0
0.781Hz
0
0
1
1.563Hz
0
1
0
3.125Hz
0
1
1
6.250Hz
1
0
0
12.5Hz
1
0
1
25Hz
1
1
0
50Hz
1
1
1
100Hz
Table 21. Motion Wake Up Function Output Data Rate
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
ODCNTL
This register is responsible for configuring ODR (output data rate) and filter settings. Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
IIR_BYPASS
Bit7
R/W
LPRO
Bit6
R/W
R/W
RESERVED RESERVED
Bit5
Bit4
R/W
OSA3
Bit3
R/W
OSA2
Bit2
R/W
R/W
OSA1
OSA0
Bit1
Bit0
2
I C Address: 0x1Bh
Reset Value
00000010
IIR_BYPASS filter bypass mode
IIR_BYPASS = 0 – filtering applied
IIR_BYPASS = 1 – filter bypassed
LPR0 low-pass filter roll off control
LPRO = 0 – filter corner frequency set to ODR/9
LPRO = 1 – filter corner frequency set to ODR/2
OSA3, OSA2, OSA1, OSA0 acceleration output data rate. The default ODR is 50Hz.
OSA3 OSA2
0
0
0
0
0
0
0
0
0
1
0
1
0
1
0
1
1
0
1
0
1
0
1
0
OSA1
0
0
1
1
0
0
1
1
0
0
1
1
OSA0
0
1
0
1
0
1
0
1
0
1
0
1
Output Data Rate
12.5Hz*
25Hz*
50Hz*
100Hz*
200Hz*
400Hz
800Hz
1600Hz
0.781Hz*
1.563Hz*
3.125Hz*
6.25Hz*
Table 22. Accelerometer Output Data Rates (ODR)
* Low power mode available, all other data rates will default to high resolution mode
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
INC1
This register controls the settings for the physical interrupt pin INT1. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
R/W
Reserved Reserved
Bit7
Bit6
R/W
IEN1
Bit5
R/W
IEA1
Bit4
R/W
IEL1
Bit3
R/W
R/W
R/W
Reserved STPOL
SPI3E
Bit2
Bit1
Bit0
2
I C Address: 0x1Ch
Reset Value
00010000
IEN enables/disables the physical interrupt pin
IEN = 0 – physical interrupt pin is disabled
IEN = 1 – physical interrupt pin is enabled
IEA sets the polarity of the physical interrupt pin
IEA = 0 – polarity of the physical interrupt pin is active low
IEA = 1 – polarity of the physical interrupt pin is active high
IEL sets the response of the physical interrupt pin
IEL = 0 – the physical interrupt pin latches until it is cleared by reading INT_REL
IEL = 1 – the physical interrupt pin will transmit one pulse with a period of 50 us
STPOL sets the polarity of Self Test
STPOL = 0 – Negative
STPOL = 1 – Positive
SPI3E sets the 3-wire SPI interface
SPI3E = 0 – disabled
SPI3E = 1 – enabled
INC2
This register controls which axis and direction of detected motion can cause an interrupt. Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
0
Bit7
R/W
0
Bit6
R/W
XNWUE
Bit5
R/W
XPWUE
Bit4
R/W
YNWUE
Bit3
R/W
YPWUE
Bit2
R/W
R/W
ZNWUE ZPWUE
Bit1
Bit0
2
I C Address: 0x1Dh
Reset Value
00111111
XNWU – x negative (x-): 0 = disabled, 1 = enabled
XPWU – x positive (x+): 0 = disabled, 1 = enabled
YNWU – y negative (y-): 0 = disabled, 1 = enabled
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
YPWU – y positive (y+): 0 = disabled, 1 = enabled
ZNWU – z negative (z-): 0 = disabled, 1 = enabled
ZPWU – z positive (z+): 0 = disabled, 1 = enabled
INC3
This register controls which axis and direction of tap/double tap can cause an interrupt. Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
0
Bit7
R/W
0
Bit6
R/W
TLEM
Bit5
R/W
TRIM
Bit4
R/W
TDOM
Bit3
R/W
TUPM
Bit2
R/W
R/W
TFDM
TFUM
Bit1
Bit0
2
I C Address: 0x1Eh
Reset Value
00111111
TLEM – x negative (x-): 0 = disabled, 1 = enabled
TRIM – x positive (x+): 0 = disabled, 1 = enabled
TDOM – y negative (y-): 0 = disabled, 1 = enabled
TUPM – y positive (y+): 0 = disabled, 1 = enabled
TFDM – z negative (z-): 0 = disabled, 1 = enabled
TFUM – z positive (z+): 0 = disabled, 1 = enabled
INC4
This register controls routing of an interrupt reporting to physical interrupt pin INT1. Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
0
Bit7
R/W
BFI1
Bit6
R/W
WMI1
Bit5
R/W
DRDYI1
Bit4
R/W
Reserved
Bit3
R/W
TDTI1
Bit2
R/W
R/W
WUFI1
TPI1
Bit1
Bit0
2
I C Address: 0x1Fh
Reset Value
00000000
BFI1 – Buffer full interrupt reported on physical interrupt pin INT1
WMI1 - Watermark interrupt reported on physical interrupt pin INT1
DRDYI1 – Data ready interrupt reported on physical interrupt pin INT1
TDTI1 - Tap/Double Tap interrupt reported on physical interrupt pin INT1
WUFI1 – Wake-Up (motion detect) interrupt reported on physical interrupt pin INT1
TPI1 – Tilt position interrupt reported on physical interrupt pin INT1
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
INC5
This register controls the settings for the physical interrupt pin INT2. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
R/W
Reserved Reserved
Bit7
Bit6
R/W
IEN2
Bit5
R/W
IEA2
Bit4
R/W
IEL2
Bit3
R/W
R/W
R/W
Reserved Reserved Reserved
Bit2
Bit1
Bit0
2
I C Address: 0x20h
Reset Value
00010000
IEN2 enables/disables the physical interrupt pin
IEN2 = 0 – physical interrupt pin is disabled
IEN2 = 1 – physical interrupt pin is enabled
IEA2 sets the polarity of the physical interrupt pin
IEA2 = 0 – polarity of the physical interrupt pin is active low
IEA2 = 1 – polarity of the physical interrupt pin is active high
IEL2 sets the response of the physical interrupt pin
IEL2 = 0 – the physical interrupt pin latches until it is cleared by reading INT_REL
IEL2 = 1 – the physical interrupt pin will transmit one pulse with a period of 50 us
INC6
This register controls routing of interrupt reporting to physical interrupt pin INT2. Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
0
Bit7
R/W
BFI2
Bit6
R/W
WMI2
Bit5
R/W
DRDYI2
Bit4
R/W
Reserved
Bit3
R/W
TDTI2
Bit2
R/W
R/W
WUFI2
TPI2
Bit1
Bit0
2
I C Address: 0x21h
Reset Value
00000000
BFI2 – Buffer full interrupt reported on physical interrupt pin INT2
WMI2 - Watermark interrupt reported on physical interrupt pin INT2
DRDYI2 – Data ready interrupt reported on physical interrupt pin INT2
TDTI2 - Tap/Double Tap interrupt reported on physical interrupt pin INT2
WUFI2 – Wake-Up (motion detect) interrupt reported on physical interrupt pin INT2
TPI2 – Tilt position interrupt reported on physical interrupt pin INT2
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
TILT_TIMER
This register is the initial count register for the tilt position state timer (0 to 255 counts). Every count is
calculated as 1/ODR delay period, where the ODR is user-defined per Table 19. A new state must be
valid as many measurement periods before the change is accepted. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
TSC7
Bit7
R/W
TSC6
Bit6
R/W
TSC5
Bit5
R/W
TSC4
Bit4
R/W
TSC3
Bit3
R/W
TSC2
Bit2
R/W
R/W
TSC1
TSC0
Bit1
Bit0
2
I C Address: 0x22h
Reset Value
00000000
WUFC
This register is the initial count register for the motion detection timer (0 to 255 counts). Every count is
calculated as 1/ODR delay period, where the ODR is user-defined per Table 21. A new state must be
valid as many measurement periods before the change is accepted. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
WUFC7
Bit7
R/W
WUFC6
Bit6
R/W
WUFC5
Bit5
R/W
WUFC4
Bit4
R/W
WUFC3
Bit3
R/W
WUFC2
Bit2
R/W
R/W
WUFC1
WUFC0
Bit1
Bit0
2
I C Address: 0x23h
Reset Value
00000000
TDTRC
This register is responsible for enableing/disabling reporting of Tap/Double Tap. Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
0
Bit7
R/W
0
Bit6
R/W
0
Bit5
R/W
0
Bit4
R/W
0
Bit3
R/W
0
Bit2
R/W
R/W
DTRE
STRE
Bit1
Bit0
2
I C Address: 0x24h
Reset Value
00000011
DTRE enables/disables the double tap interrupt
DTRE = 0 – do not update/trigger interrupts on doubple tap events
DTRE = 1 –update interrupts on double tap events
STRE enables/disables single tap interrupt
STRE = 0 – do not update/trigger interrupts on single tap events
STRE = 1 –update interrupts on single tap events
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
TDTC
This register contains counter information for the detection of a double tap event. When the Directional
TapTM ODR is 400Hz or less, every count is calculated as 1/ODR delay period. When the Directional
TapTM ODR is 800Hz, every count is calculated as 2/ODR delay period. When the Directional TapTM
ODR is 1600Hz, every count is calculated as 4/ODR delay period. The Directional TapTM ODR is
user-defined per Table 20. The TDTC counts starts at the beginning of the fist tap and it represents
the minimum time separation between the first tap and the second tap in a double tap event. More
speficifcally, the second tap event must end outside of the TDTC. The Kionix recommended default
value is 0.3 seconds (0x78h). Note that to properly change the value of this register, the PC1 bit in
CTRL_REG1 must first be set to “0”.
R/W
TDTC7
Bit7
R/W
TDTC6
Bit6
R/W
TDTC5
Bit5
R/W
TDTC4
Bit4
R/W
TDTC3
Bit3
R/W
TDTC2
Bit2
R/W
R/W
TDTC1
TDTC0
Bit1
Bit0
2
I C Address: 0x25h
Reset Value
01111000
TTH
This register represents the 8-bit jerk high threshold to determine if a tap is detected. Though this is an
8-bit register, the register value is internally multiplied by two in order to set the high threshold. This
multiplication results in a range of 0d to 510d with a resolution of two counts. The Performance Index
(PI) is the jerk signal that is expected to be less than this threshold, but greater than the TTL threshold
during single and double tap events. Note that to properly change the value of this register, the PC1 bit
in CTRL_REG1 must first be set to “0”. The Kionix recommended default value is 203 (0xCBh) and the
Performance Index is calculated as:
X’ = X(current) – X(previous)
Y’ = Y(current) – Y(previous)
Z’ = Z(current) – Z(previous)
PI = |X’| + |Y’| + |Z’|
Equation 1. Performance Index
`
R/W
TTH7
Bit7
R/W
TTH6
Bit6
R/W
TTH5
Bit5
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R/W
TTH4
Bit4
R/W
TTH3
Bit3
R/W
TTH2
Bit2
R/W
R/W
TTH1
TTH0
Bit1
Bit0
2
I C Address: 0x26h
Reset Value
11001011
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Page 50 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
TTL
This register represents the 8-bit (0d– 255d) jerk low threshold to determine if a tap is detected. The
Performance Index (PI) is the jerk signal that is expected to be greater than this threshold and less
than the TTH threshold during single and double tap events. The Kionix recommended default value is
26 (0x1Ah). Note that to properly change the value of this register, the PC1 bit in CTRL_REG1 must
first be set to “0”.
R/W
TTL7
Bit7
R/W
TTL6
Bit6
R/W
TTL5
Bit5
R/W
TTL4
Bit4
R/W
TTL3
Bit3
R/W
TTL2
Bit2
R/W
R/W
TTL1
TTL0
Bit1
Bit0
2
I C Address: 0x27h
Reset Value
00011010
FTD
This register contains counter information for the detection of any tap event. When the Directional
TapTM ODR is 400Hz or less, every count is calculated as 1/ODR delay period. When the Directional
TapTM ODR is 800Hz, every count is calculated as 2/ODR delay period. When the Directional TapTM
ODR is 1600Hz, every count is calculated as 4/ODR delay period. The Directional TapTM ODR is
user-defined per Table 20. In order to ensure that only tap events are detected, these time limits are
used. A tap event must be above the performance index threshold for at least the low limit (FTDL0 –
FTDL2) and no more than the high limit (FTDH0 – FTDH4). The Kionix recommended default value for
the high limit is 0.05 seconds and for the low limit is 0.005 seconds (0xA2h). Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
FTDH4
Bit7
R/W
FTDH3
Bit6
R/W
FTDH2
Bit5
R/W
FTDH1
Bit4
R/W
FTDH0
Bit3
R/W
FTDL2
Bit2
R/W
R/W
FTDL1
FTDL0
Bit1
Bit0
2
I C Address: 0x28h
Reset Value
10100010
STD
This register contains counter information for the detection of a double tap event. When the Directional
TapTM ODR is 400Hz or less, every count is calculated as 1/ODR delay period. When the Directional
TapTM ODR is 800Hz, every count is calculated as 2/ODR delay period. When the Directional TapTM
ODR is 1600Hz, every count is calculated as 4/ODR delay period. The Directional TapTM ODR is userdefined per Table 20. In order to ensure that only tap events are detected, this time limit is used. This
register sets the total amount of time that the two taps in a double tap event can be above the PI
threshold (TTL). The Kionix recommended default value for STD is 0.09 seconds (0x24h). Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
R/W
STD7
Bit7
R/W
STD6
Bit6
R/W
STD5
Bit5
R/W
STD4
Bit4
R/W
STD3
Bit3
R/W
STD2
Bit2
R/W
R/W
STD1
STD0
Bit1
Bit0
2
I C Address: 0x29h
KX023-1025
Rev. 10.0
Apr-2015
Reset Value
00100100
TLT
This register contains counter information for the detection of a tap event. When the Directional Tap TM
ODR is 400Hz or less, every count is calculated as 1/ODR delay period. When the Directional Tap TM
ODR is 800Hz, every count is calculated as 2/ODR delay period. When the Directional TapTM ODR is
1600Hz, every count is calculated as 4/ODR delay period. The Directional TapTM ODR is userdefined per Table 20. In order to ensure that only tap events are detected, this time limit is used. This
register sets the total amount of time that the tap algorithm will count samples that are above the PI
threshold (TTL) during a potential tap event. It is used during both single and double tap events.
However, reporting of single taps on the physical interrupt pin INT1 or INT2 will occur at the end of the
TWS. The Kionix recommended default value for TLT is 0.1 seconds (0x28h). Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
TLT7
Bit7
R/W
TLT6
Bit6
R/W
TLT5
Bit5
R/W
TLT4
Bit4
R/W
TLT3
Bit3
R/W
TLT2
Bit2
R/W
R/W
TLT1
TLT0
Bit1
Bit0
2
I C Address: 0x2Ah
Reset Value
00101000
TWS
This register contains counter information for the detection of single and double taps. When the
Directional TapTM ODR is 400Hz or less, every count is calculated as 1/ODR delay period. When the
Directional TapTM ODR is 800Hz, every count is calculated as 2/ODR delay period. When the
Directional TapTM ODR is 1600Hz, every count is calculated as 4/ODR delay period. The Directional
TapTM ODR is user-defined per Table 20. It defines the time window for the entire tap event, single or
double, to occur. Reporting of single taps on the physical interrupt pin INT1 or INT2 will occur at the
end of this tap window. The Kionix recommended default value for TWS is 0.4 seconds (0xA0h). Note
that to properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
TWS7
Bit7
R/W
TWS6
Bit6
R/W
TWS5
Bit5
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R/W
TWS4
Bit4
R/W
TWS3
Bit3
R/W
TWS2
Bit2
R/W
R/W
TWS1
TWS0
Bit1
Bit0
2
I C Address: 0x2Bh
Reset Value
10100000
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Page 52 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
ATH
This register sets the threshold for wake-up (motion detect) interrupt is set. The KX023 will ship from
the factory with this value set to correspond to a change in acceleration of 0.5g. Note that to properly
change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
ATH7
Bit7
R/W
ATH6
Bit6
R/W
ATH5
Bit5
R/W
ATH4
Bit4
R/W
ATH3
Bit3
R/W
ATH2
Bit2
R/W
R/W
ATH1
ATH0
Bit1
Bit0
2
I C Address: 0x30h
Reset Value
00001000
TILT_ANGLE_LL
This register sets the low level threshold for tilt angle detection. The KX023 ships from the factory with
tilt angle set to a low threshold of 22° from horizontal. A different default tilt angle can be requested
from the factory. Note that the minimum suggested tilt angle is 10°. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
TA7
Bit7
R/W
TA6
Bit6
R/W
TA5
Bit5
R/W
TA4
Bit4
R/W
TA3
Bit3
R/W
TA2
Bit2
R/W
TA1
Bit1
R/W
TA0
Bit0
Reset Value
00001100
2
I C Address: 0x32h
TILT_ANGLE_HL
This register sets the high level threshold for tilt angle detection. Note that to properly change the value
of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
HL7
HL6
HL5
HL4
HL3
HL2
HL1
HL0
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
00101010
2
I C Address: 0x33h
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Page 53 of 74
PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
HYST_SET
This register sets the Hysteresis that is placed in between the Screen Rotation states. The KX023
ships from the factory with HYST_SET set to +/-15° of hysteresis. A different default hysteresis can be
requested from the factory. Note that when writing a new value to this register the current values of
RES0 and RES1 must be preserved. These values are set at the factory and must not change. Note
that to properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
RES1
Bit7
R/W
RES0
Bit6
R/W
HYST5
Bit5
R/W
HYST4
Bit4
R/W
HYST3
Bit3
R/W
HYST2
Bit2
R/W
R/W
HYST1
HYST0
Bit1
Bit0
2
I C Address: 0x34h
Reset Value
00010100
LP_CNTL
Low Power Control sets the number of samples of accelerometer output to be averaged. Note that to
properly change the value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
Reserved
Bit7
R/W
AVC2
Bit6
R/W
AVC1
Bit5
R/W
AVC0
Bit4
R/W
R/W
R/W
Reserved Reserved Reserved
Bit3
Bit2
Bit1
R/W
Reserved
Bit0
Reset Value
01001011
2
I C Address: 0x35h
AVC – Averaging Filter Control, the default seting is 16 samples averaged
000 = No Averaging
001 = 2 Samples Averaged
010 = 4 Samples Averaged
011 = 8 Samples Averaged
100 = 16 Samples Averaged (default)
101 = 32 Samples Averaged
110 = 64 Samples Averaged
111 = 128 Samples Averaged
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BUF_CNTL1
Read/write control register that controls the buffer sample threshold. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
Bit7
R/W
SMP6
Bit6
R/W
SMP5
Bit5
R/W
SMP4
Bit4
R/W
SMP3
Bit3
R/W
SMP2
Bit2
R/W
R/W
SMP1
SMP0
Bit1
Bit0
2
I C Address: 0x3Ah
Reset Value
00000000
SMP_TH[6:0] Sample Threshold; determines the number of samples that will trigger a
watermark interrupt or will be saved prior to a trigger event. When BUF_RES=1, the
maximum number of samples is 41; when BUF_RES=0, the maximum number of
samples is 84.
Buffer Model
Sample Function
Bypass
None
FIFO
Stream
Trigger
FILO
Specifies how many buffer sample are needed
to trigger a watermark interrupt.
Specifies how many buffer samples are needed
to trigger a watermark interrupt.
Specifies how many buffer samples before the
trigger event are retained in the buffer.
Specifies how many buffer samples are needed
to trigger a watermark interrupt.
Table 23. Sample Threshold Operation by Buffer Mode
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BUF_CNTL2
Read/write control register that controls sample buffer operation. Note that to properly change the
value of this register, the PC1 bit in CTRL_REG1 must first be set to “0”.
R/W
BUFE
Bit7
R/W
BRES
Bit6
R/W
BFIE
Bit5
R/W
0
Bit4
R/W
0
Bit3
R/W
0
Bit2
R/W
R/W
BUF_M1 BUF_M0
Bit1
Bit0
2
I C Address: 0x3Bh
Reset Value
00000000
BUFE controls activation of the sample buffer.
BUFE = 0 – sample buffer inactive
BUFE = 1 – sample buffer active
BRES determines the resolution of the acceleration data samples collected by the sample
buffer.
BUF_RES = 0 – 8-bit samples are accumulated in the buffer
BUF_RES = 1 – 16-bit samples are accumulated in the buffer
BFIE buffer full interrupt enable bit
BFIE = 0 – buffer full interrupt disabled
BFIE = 1 – buffer full interrupt updated in INS2
BUF_M1, BUF_M0 selects the operating mode of the sample buffer per Table 24.
BUF_M1
BUF_M0
0
0
0
1
1
0
1
1
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Mode
Description
The buffer collects 84 sets of 8-bit low resolution values or 41
FIFO
sets of 16bit high resolution values and then stops collecting
data, collecting new data only when the buffer is not full.
The buffer holds the last 84 sets of 8-bit low resolution values
Stream
or 41 sets of 16bit high resolution values. Once the buffer is
full, the oldest data is discarded to make room for newer data.
When a trigger event occurs, the buffer holds the last data set
of SMP[6:0] samples before the trigger event and then
Trigger
continues to collect data until full. New data is collected only
when the buffer is not full.
The buffer holds the last 84 sets of 8-bit low resolution values
or 41 sets of 16bit high resolution values. Once the buffer is
FILO
full, the oldest data is discarded to make room for newer data.
Reading from the buffer in this mode will return the most
recent data first.
Table 24. Selected Buffer Mode
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BUF_STATUS_1
This register reports the status of the sample buffer.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
SMP_LEV7 SMP_LEV6 SMP_LEV5 SMP_LEV4 SMP_LEV3 SMP_LEV2 SMP_LEV1 SMP_LEV0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
2
I C Address: 0x3Ch
SMP_LEV[7:0] Sample Level; reports the number of data bytes that have been stored in the
sample buffer. When BUF_RES=1, this count will increase by 6 for each 3-axis
sample in the buffer; when BUF_RES=0, the count will increase by 3 for each 3-axis
sample. If this register reads 0, no data has been stored in the buffer.
BUF_STATUS_2
This register reports the status of the sample buffer trigger function.
R/W
BUF_TRIG
Bit7
R/W
0
Bit6
R/W
0
Bit5
R/W
0
Bit4
R/W
0
Bit3
R/W
0
Bit2
R/W
R/W
0
0
Bit1
Bit0
2
I C Address: 0x3Dh
BUF_TRIG reports the status of the buffer’s trigger function if this mode has been selected.
When using trigger mode, a buffer read should only be performed after a trigger event.
BUF_CLEAR
Latched buffer status information and the entire sample buffer are cleared when any data is written to
this register.
R/W
X
Bit7
R/W
X
Bit6
R/W
X
Bit5
R/W
X
Bit4
R/W
X
Bit3
R/W
X
Bit2
R/W
R/W
X
X
Bit1
Bit0
2
I C Address: 0x3Eh
R/W
X
Bit4
R/W
X
Bit3
R/W
X
Bit2
R/W
R/W
X
X
Bit1
Bit0
2
I C Address: 0x3Fh
BUF_READ
Buffer output register
R/W
X
Bit7
R/W
X
Bit6
R/W
X
Bit5
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SELF_TEST
When 0xCA is written to this register, the MEMS self-test function is enabled. Electrostatic-actuation of
the accelerometer, results in a DC shift of the X, Y and Z axis outputs. Writing 0x00 to this register will
return the accelerometer to normal operation.
R/W
1
Bit7
R/W
1
Bit6
R/W
0
Bit5
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R/W
0
Bit4
R/W
1
Bit3
R/W
0
Bit2
R/W
R/W
1
0
Bit1
Bit0
2
I C Address: 0x60h
Reset Value
00000000
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PART NUMBER:
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Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
KX023 Embedded Applications
Orientation Detection Feature
The orientation detection feature of the KX023 will report changes in face up, face down, +/- vertical and +/horizontal orientation. This intelligent embedded algorithm considers very important factors that provide
accurate orientation detection from low cost tri-axis accelerometers. Factors such as: hysteresis, device
orientation angle and delay time are described below as these techniques are utilized inside the KX023
Hysteresis
A 45° tilt angle threshold seems like a good choice because it is halfway between 0° and 90°. However,
a problem arises when the user holds the device near 45°. Slight vibrations, noise and inherent sensor
error will cause the acceleration to go above and below the threshold rapidly and randomly, so the
screen will quickly flip back and forth between the 0° and the 90° orientations. This problem is avoided
in the KX023 by choosing a 30° threshold angle. With a 30° threshold, the screen will not rotate from 0°
to 90° until the device is tilted to 60° (30° from 90°). To rotate back to 0°, the user must tilt back to 30°,
thus avoiding the screen flipping problem. This example essentially applies +/- 15° of hysteresis in
between the four screen rotation states. Table 25 shows the acceleration limits implemented for T
=30°.
Orientation X Acceleration (g) Y Acceleration (g)
0°/360°
-0.5 < ax < 0.5
ay > 0.866
90°
ax > 0.866
-0.5 < ay < 0.5
180°
-0.5 < ax < 0.5
ay < -0.866
270°
ax < -0.866
-0.5 < ay < 0.5
Table 25. Acceleration at the four orientations with +/- 15° of hysteresis
The KX023 allows the user to change the amount of hysteresis in between the four screen rotation
states. By simply writing to the HYST_SET register, the user can adjust the amount of hysteresis up to
+/- 45°. The plot in Figure 8 shows the typical amount of hysteresis applied for a given digital count
value of HYST_SET.
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HYST_SET vs Hysteresis
50
45
Hysteresis (+/- degrees)
40
35
30
25
Hysteresis
20
15
10
5
0
0
5
10
15
20
25
30
HYST_SET Value (Counts)
Figure 8. HYST_SET vs Hysteresis
Device Orientation Angle (aka Tilt Angle)
To ensure that horizontal and vertical device orientation changes are detected, even when it isn’t in the
ideal vertical orientation – where the angle θ in Figure 9 is 90°, the KX023 considers device orientation
angle in its algorithm.
Angle
Figure 9. Device Orientation Angle
As the angle in Figure 9 is decreased, the maximum gravitational acceleration on the X-axis or Y-axis
will also decrease. Therefore, when the angle becomes small enough, the user will not be able to make
the screen orientation change. When the device orientation angle approaches 0° (device is flat on a
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desk or table), ax = ay = 0g, az = +1g, and there is no way to determine which way the screen should be
oriented, the internal algorithm determines that the device is in either the face-up or face-down
orientation, depending on the sign of the z-axis. The KX023 will only change the screen orientation
when the orientation angle is above the factory-defaulted/user-defined threshold set in the
TILT_ANGLE register. Equation 2 can be used to determine what value to write to the TILT_ANGLE
register to set the device orientation angle. The value for TILT_ANGLE_HL is preset at the factory but
can be adjusted in special cases (e.g. to reduce the effect of transient g-variation such as when device
is being moved rather than just being rotated).
TILT_ANGLE (counts) = sin θ * (32 (counts/g))
Equation 2. Tilt Angle Threshold
Tilt Timer
The 8-bit register, TILT_TIMER can be used to qualify changes in orientation. The KX023 does this by
incrementing a counter with a size that is specified by the value in TILT_TIMER for each set of
acceleration samples to verify that a change to a new orientation state is maintained. A user defined
output data rate (ODR) determines the time period for each sample. Equation 3 shows how to
calculate the TILT_TIMER register value for a desired delay time.
TILT_TIMER (counts) = Delay Time (sec) x ODR (Hz)
Equation 3. Tilt Position Delay Time
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Motion Interrupt Feature Description
The Motion interrupt feature of the KX023 reports qualified changes in the high-pass filtered acceleration
based on the Wake Up (ATH) threshold. If the high-pass filtered acceleration on any axis is greater than the
user-defined wake up threshold (ATH), the device has transitioned from an inactive state to an active state.
Equation 4 shows how to calculate the ATH register value for a desired wake up threshold. Note that this
calculation varies based on the configured g-range of the part.
ATH (counts) = Wake Up Threshold (g) x Sensitivity (counts/g)
Equation 4. Wake Up Threshold
An 8-bit raw unsigned value represents a counter that permits the user to qualify each active/inactive state
change. Note that each WUFC Timer count qualifies 1 (one) user-defined ODR period (OWUF). Equation 5
shows how to calculate the WUFC register value for a desired wake up delay time.
WUFC (counts) = Wake Up Delay Time (sec) x OWUF (Hz)
Equation 5. Wake Up Delay Time
The latched motion interrupt response algorithm works as following: while the part is in inactive state, the
algorithm evaluates differential measurement between each new acceleration data point with the preceding
one and evaluates it against the ATH threshold. When the differential measurement is greater than ATH
threshold, the wakeup counter starts the count. Differential measurements are now calculated based on the
difference between the current acceleration and the acceleration when the counter started. The part will report
that motion has occurred at the end of the count assuming each differential measurement has remained above
the threshold. If at any moment during the count the differential measurement falls below the threshold, the
counter will stop the count and the part will remain in inactive state.
To illustrate how the algorithm works, consider the Figure 10 below that shows the latched response of the
motion detection algorithm with WUF Timer (WUFC) set to 10 counts. Note how the difference between the
acceleration sample marked in red and the one marked in green resulted in a differential measurements
represented with orange bar being above the WUF threshold. At this point, the counter begins to count number
of counts stored in WUFC register and the wakeup algorithm will evaluate the difference between each new
acceleration measurement and the measurement marked in green that will remain a reference measurement
for the duration of the counter count. At the end of the count, assuming all differential measurements were
larger than WUF threshold, as is the case in the example showed in Figure 10, a motion event will be reported.
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Figure 10. Latched Motion Interrupt Response
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Directional Tap Detection Feature Description
The Directional Tap Detection feature of the KX023 recognizes single and double tap inputs and reports the
acceleration axis and direction that each tap occurred. Eight performance parameters, as well as a userselectable ODR are used to configure the KX023 for a desired tap detection response.
Performance Index
The Directional TapTM detection algorithm uses low and high thresholds to help determine when a tap event
has occurred. A tap event is detected when the previously described jerk summation exceeds the low
threshold (TTL) for more than the tap detection low limit, but less than the tap detection high limit as contained
in FTD. Samples that exceed the high limit (TTH) will be ignored. Figure 11 shows an example of a single tap
event meeting the performance index criteria.
Calculated Performance Index
PI
180
: Sampled Data
160
140
jerk (counts)
120
100
80
60
40
TTL
20
0
3.14
3.15
3.16
3.17
3.18
time(sec)
3.19
3.2
3.21
Figure 11. Jerk Summation vs Threshold
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Single Tap Detection
The latency timer (TLT) sets the time period that a tap event will only be characterized as a single tap.
A second tap has to occur outside of the latency timer. If a second tap occurs inside the latency time, it
will be ignored as it occurred too quickly. The single tap will be reported at the end of the TWS. Figure
12 shows a single tap event meeting the PI, latency and window requirements.
Calculated Performance Index
160
PI
140
TWS
120
jerk (counts)
100
TLT
80
60
40
TTL
20
0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
time(sec)
2.8
2.9
3
3.1
Figure 12. Single Directional TapTM Timing
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Double Tap Detection
An event can be characterized as a double tap if the second tap crosses up the performance index
(TTL) inside the TWS period and ends outside the TDTC. This means that the TDTC determines the
minimum time separation that must exist between the two taps of a double tap event. Similar to the
single tap, the first tap event must exceed the performance index for the time limit contained in FTD.
Also, the duration when the first and second events combined exceed the performance index should
not exceed STD. The double tap will be reported at the end of the second TLT. Figure 13 shows a
double tap event meeting the PI, latency and window requirements.
Figure 13. Double Directional TapTM Timing
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Sample Buffer Feature Description
The sample buffer feature of the KX023 accumulates and outputs acceleration data based on how it is
configured. There are 4 buffer modes available, and samples can be accumulated at either low (8-bit) or high
(16-bit) resolution. Acceleration data is collected at the ODR specified by OSAA:OSAD in the Output Data
Control Register. Each buffer mode accumulates data, reports data, and interacts with status indicators in a
slightly different way.
FIFO Mode
Data Accumulation
Sample collection stops when the buffer is full.
Data Reporting
Data is reported with the oldest byte of the oldest sample first (X_L or X based
on resolution).
Status Indicators
A watermark interrupt occurs when the number of samples in the buffer reaches
the Sample Threshold. The watermark interrupt stays active until the buffer
contains less than this number of samples. This can be accomplished through
clearing the buffer or explicitly reading greater than SMPX samples (calculated
with Equation 6).
BUF_RES=0:
SMPX = SMP_LEV[7:0] / 3 – SMP_TH[6:0]
BUF_RES=1:
SMPX = SMP_LEV[7:0] / 6 – SMP_TH[6:0]
Equation 6. Samples Above Sample Threshold
Stream Mode
Data Accumulation
Sample collection continues when the buffer is full; older data is discarded to
make room for newer data.
Data Reporting
Data is reported with the oldest sample first (uses FIFO read pointer).
Status Indicators
A watermark interrupt occurs when the number of samples in the buffer reaches
the Sample Threshold. The watermark interrupt stays active until the buffer
contains less than this number of samples. This can be accomplished through
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clearing the buffer or explicitly reading greater than SMPX samples (calculated
with Equation 1).
Trigger Mode
Data Accumulation
When a physical interrupt is caused by one of the digital engines or when a logic
high signal occurs on the TRIG pin, the trigger event is asserted and SMP[6:0]
samples prior to the event are retained. Sample collection continues until the
buffer is full.
Data Reporting
Data is reported with the oldest sample first (uses FIFO read pointer).
Status Indicators
When a physical interrupt occurs and there are at least SMP[6:0] samples in the
buffer, BUF_TRIG in BUF_STATUS_REG2 is asserted.
FILO Mode
Data Accumulation
Sample collection continues when the buffer is full; older data is discarded to
make room for newer data.
Data Reporting
Data is reported with the newest byte of the newest sample first (Z_H or Z based
on resolution).
Status Indicators
A watermark interrupt occurs when the number of samples in the buffer reaches
the Sample Threshold. The watermark interrupt stays active until the buffer
contains less than this number of samples. This can be accomplished through
clearing the buffer or explicitly reading greater than SMPX samples (calculated
with Equation 1).
Buffer Operation
The following diagrams illustrate the operation of the buffer conceptually. Actual physical
implementation has been abstracted to offer a simplified explanation of how the different buffer
modes operate. Figure 14 represents a high-resolution 3-axis sample within the buffer. Figure
15 - Figure 23 represent a 10-sample version of the buffer (for simplicity), with Sample
Threshold set to 8.
Regardless of the selected mode, the buffer fills sequentially, one byte at a time. Figure 14
shows one 6-byte data sample. Note the location of the FILO read pointer versus that of the
FIFO read pointer.
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buffer write pointer --
Index
0
1
2
3
4
5
6
Byte
X_L
X_H
Y_L
Y_H
Z_L
Z_H
KX023-1025
Rev. 10.0
Apr-2015
-- FIFO read pointer
-- FILO read pointer
Figure 14. One Buffer Sample
Regardless of the selected mode, the buffer fills sequentially, one sample at a time. Note in
Figure 15 the location of the FILO read pointer versus that of the FIFO read pointer. The buffer
write pointer shows where the next sample will be written to the buffer.
buffer write pointer →
Index
Sample
0
Data0
1
Data1
2
Data2
← FIFO read pointer
← FILO read pointer
3
4
5
6
7
← Sample Threshold
8
9
Figure 15. Buffer Filling
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The buffer continues to fill sequentially until the Sample Threshold is reached. Note in Figure
16 the location of the FILO read pointer versus that of the FIFO read pointer.
buffer write pointer →
Index
Sample
0
Data0
1
Data1
2
Data2
3
Data3
4
Data4
5
Data5
6
Data6
7
← FIFO read pointer
← FILO read pointer
← Sample Threshold
8
9
Figure 16. Buffer Approaching Sample Threshold
In FIFO, Stream, and FILO modes, a watermark interrupt is issued when the number of
samples in the buffer reaches the Sample Threshold. In trigger mode, this is the point where
the oldest data in the buffer is discarded to make room for newer data.
buffer write pointer →
Index
0
1
2
3
4
5
6
7
8
9
Sample
Data0
Data1
Data2
Data3
Data4
Data5
Data6
Data7
← FIFO read pointer
← Sample Threshold/FILO read pointer
Figure 17. Buffer at Sample Threshold
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In trigger mode, data is accumulated in the buffer sequentially until the Sample Threshold is
reached. Once the Sample Threshold is reached, the oldest samples are discarded when new
samples are collected. Note in Figure 18 how Data0 was thrown out to make room for Data8.
Trigger write pointer →
Index
0
1
2
3
4
5
6
7
8
9
Sample
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
← Trigger read pointer
← Sample Threshold
Figure 18. Additional Data Prior to Trigger Event
After a trigger event occurs, the buffer no longer discards the oldest samples, and instead
begins accumulating samples sequentially until full. The buffer then stops collecting samples,
as seen in Figure 19. This results in the buffer holding SMP_TH[6:0] samples prior to the
trigger event, and SMPX samples after the trigger event.
Index
Sample
0
1
2
3
4
5
6
Data1
Data2
Data3
Data4
Data5
Data6
Data7
← Trigger read pointer
7
8
9
Data8
Data9
Data10
← Sample Threshold
Figure 19. Additional Data After Trigger Event
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
In FIFO, Stream, FILO, and Trigger (after a trigger event has occurred) modes, the buffer
continues filling sequentially after the Sample Threshold is reached. Sample accumulation after
the buffer is full depends on the selected operation mode. FIFO and Trigger modes stop
accumulating samples when the buffer is full, and Stream and FILO modes begin discarding the
oldest data when new samples are accumulated.
Index
0
1
2
3
4
5
6
7
8
9
Sample
Data0
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
Data9
← FIFO read pointer
← Sample Threshold
← FILO read pointer
Figure 20. Buffer Full
After the buffer has been filled in FILO or Stream mode, the oldest samples are discarded when
new samples are collected. Note in Figure 21how Data0 was thrown out to make room for
Data10.
Index
0
1
2
3
4
5
6
7
8
9
Sample
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Data8
Data9
Data10
← FIFO read pointer
← Sample Threshold
← FILO read pointer
Figure 21. Buffer Full – Additional Sample Accumulation in Stream or FILO Mode
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
In FIFO, Stream, or Trigger mode, reading one sample from the buffer will remove the oldest
sample and effectively shift the entire buffer contents up, as seen in Figure 22.
buffer write pointer →
Index
Sample
0
Data1
1
Data2
2
Data3
3
Data4
4
Data5
5
Data6
6
Data7
7
Data8
8
Data9
← FIFO read pointer
← Sample Threshold
← FILO read pointer
9
Figure 22. FIFO Read from Full Buffer
In FILO mode, reading one sample from the buffer will remove the newest sample and leave
the older samples untouched, as seen in Figure 23.
buffer write pointer →
Index
0
1
2
3
4
5
6
Sample
Data0
Data1
Data2
Data3
Data4
Data5
Data6
7
Data7
8
Data8
← FIFO read pointer
← Sample Threshold
← FILO read pointer
9
Figure 23. FILO Read from Full Buffer
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tel: 607-257-1080 – fax:607-257-1146
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PART NUMBER:
± 2g / 4g / 8g Tri-axis Digital
Accelerometer Specifications
KX023-1025
Rev. 10.0
Apr-2015
Revision History
REVISION
1.0
1.1
1.2
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
DESCRIPTION
Initial Release
Added Offset and Sensitivity Tolerances
Added LP_CNTL Accelerometer Output Averaging Register, Updated Test
Spec limits Table 6 and I2C timing Table 9
Added reference to FlexSet™ Performance Optimization, Updated reference
to OSA in ODCNTL for output registers.
Updated default values for TSPP, TSCP
Added Min and Max Self Test limits to Table 1, replaced bottom view of
package in diagrams.pictures.
Improved high resolution and low power mode descriptions, corrected test
specification limits Table 6.
Administrative adjustment
Revised Accelerometer Outputs table
Updated Package Drawing
Revised ODR settings and current profile
Added Power-On procedure details.
Updated Figure 1.
Updated Figure 10 and the description of the Motion Interrupt feature.
Updated Figure 13 and the description of Double-Tap Detection.
Fixed factory value set for TILT_ANGLE_LL.
Updated references to Tables and Figures.
DATE
30-Aug-2013
12-Sept-2013
02-Oct-2013
19-Nov-2013
03-Dec-2013
08-Jan-2014
16-Jan-2014
17-Sep-2014
15-Oct-2014
08-Dec-2014
01-Apr-2015
"Kionix" is a registered trademark of Kionix, Inc. Products described herein are protected by patents issued or pending. No license is granted by implication or otherwise
under any patent or other rights of Kionix. The information contained herein is believed to be accurate and reliable but is not guaranteed. Kionix does not assume
responsibility for its use or distribution. Kionix also reserves the right to change product specifications or discontinue this product at any time without prior notice. This
publication supersedes and replaces all information previously supplied.
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tel: 607-257-1080 – fax:607-257-1146
www.kionix.com - info@kionix.com
© 2015 Kionix – All Rights Reserved
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