AN075
Replacing KX022 with KX122 Accelerometer
36 Thornwood Dr. — Ithaca, NY 14850 USA
Tel: 607-257-1080 — Fax: 607-257-1146
www.kionix.com — info@kionix.com
© Kionix 2017 All Rights Reserved
2 June 2017
Page 1 of 8
Introduction
The purpose of this application note is to illustrate how the Kionix KX122 accelerometer
can replace an existing Kionix KX022 accelerometer.
Pin Compatibility
The KX022 accelerometer can be easily replaced by a KX122 accelerometer for either an
I2C or SPI interface application. From a hardware perspective, the KX122 is a drop-in
replacement for the KX022. Both parts are 2x2x0.9mm in size and have identical pad/pin
layouts.
KX022
KX122
Pin
Name
1
SDO/ADDR
2
SDI/SDA
3
IO_VDD
4
TRIG
5
INT1
6
INT2
7
VDD
8
GND
9
GND
10
nCS
11
NC
12
SCLK/SCL
Pin
Name
Description
1
SDO/ADDR
Serial Data Out pin during 4 wire SPI
communication and part of the device address
during I2C communication.
2
SDI/SDA
SPI Data input / I2C Serial Data
3
IO_VDD
The power supply input for the digital
communication bus. Optionally decouple this pin to
ground with a 0.1uF ceramic capacitor.
4
TRIG
Trigger pin for FIFO buffer control - Connect to
GND when not using external trigger option
5
INT1
Physical Interrupt 1. Leave floating if not used.
6
INT2
Physical Interrupt 2. Leave floating if not used.
7
VDD
The power supply input. Decouple this pin to
ground with a 0.1uF ceramic capacitor.
8
GND
Ground
9
GND
Ground
10
nCS
Chip Select (active LOW) for SPI communication.
Connect to IO_VDD for I2C communication. Do not
leave floating.
11
NC
Not Internally Connected - Can be connected to
VDD, IO_VDD, GND or leave floating.
12
SCLK/SCL
SPI and I2C Serial Clock
Figure 1: Pin Description for KX022 and KX122
AN075
© Kionix 2017 All Rights Reserved
2 June 2017
Page 2 of 8
Key Similarities
KX122 and KX022 accelerometer outputs are both 16-bit.
KX122 and KX022 share identical register mappings, with the exception that the KX122
has more registers / bits that were previously reserved in the KX022 to support additional
features. Any software register control currently written for the KX022, will work
seamlessly with the KX122. Interrupt control and configurations registers are identical
(mapping).
KX122 and KX022 also share the same embedded application engines. Any software
currently controlling the KX022 application engines, will inherently work for the KX122.
This means no changes to threshold and/or timer settings will be required.
Key Differences
New Features:
o The KX022 is a first-generation design of a high performance, feature-rich
accelerometer. The KX122 is a second-generation design that additionally offers:
Free-fall Engine: An embedded application engine that offers notification
when the accelerometer senses a free-fall event.
2048-byte Sample Buffer: This buffer is eight (8) times larger than the
KX022’s
Higher Sample Rates (up to 25.6kHz)
KX022 offers ODR settings of 0.781Hz, 1.563Hz, 3.125Hz, 6.25Hz,
12.5Hz, 25Hz, 50Hz, 100Hz, 200Hz, 400Hz, 800Hz, and 1600Hz.
KX122 offers the same ODR settings as KX022, but additionally
offers 3200Hz, 6400Hz, 12800Hz, and 25600Hz.
Buffer Operation:
o Buffer Size
KX022 buffer size is 256 bytes – up to 84 (8-bit) and 41 (16-bit) samples
can be stored.
KX122 buffer size is 2048 bytes – up to 681 (8-bit) and 340 (16-bit)
samples can be stored.
o Buffer Auto-Clear
KX022 doesn’t clear the content of the buffer after buffer is disabled. The
content of the buffer will remain the same until (1) the data is read out or
(2) the buffer is cleared.
KX122 clears the content of the buffer after buffer is disabled. The
content of the buffer will remain the same until (1) the data is read out or
(2) the buffer is cleared or (3) the buffer is disabled.