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tel: 607-257-1080 – fax:607-257-1146
www.kionix.com - info@kionix.com
AN 046
KX022 and KX023 Supplemental Offset Calibration
© Kionix 2015
21 July 2015
Page 1 of 5
Introduction
Kionix calibrates the offset of the KX022 and KX023 at the factory. After
assembly, it is sometimes found by the customer that there is a subsequent
offset shift.
The KX022 and KX023 have embedded registers used to provide a final
factory calibration. These registers have the default factory calibration but
also they can be adjusted by a user programmatically for an additional offset
adjustment to the original factory programmed calibration.
The values for the user applied offset adjustment are stored in RAM and must
be updated by the controlling system after each power up or reset.
Offset Calibration readings and adjustments are calculated using 2g High RES
mode.
The Offset calibration adjustment adds a constant value to correct for an
offset error.
Two registers are employed to make the Offset Calibration adjustment.
AN 046
© Kionix 2015
21 July 2015
Page 2 of 5
Offset Calibration Registers:
The offset correction registers XCAL (1Dh), YCAL(1Eh), and ZCAL (1Fh) are located on
memory page 1 and not memory page 0.
To write to the calibration registers simply write 0x01h to address 0x7Fh to switch to
memory page 1.
Then write your correction values for XCAL, YCAL and ZCAL registers.
Switch back to memory page 0 by writing 0x00h to address 0x7Fh
OUT_CNTL
Output Data Control
Register
Page
Addr
R/W
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit3
Bit 2
Bit 1
Bit 0
OUT_CNTL
01h
1Ch
R/W
OTP
RSVD
RSVD
RSVD
RSVD
0
0
CALRES<1>
CALRES<0>
CALRES<1:0> - Digital calibration resolution select
00 = 0.24mg/count
01 = 0.48mg/count
10 = 0.96mg/count
11 = 1.92mg/count
The Output Data Control Register allows for a choice between the range and the
resolution of the Offset adjustment correction value.
Accelerometer digital offset calibration
Register
Page
Addr
R/W
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit3
Bit 2
Bit 1
Bit 0
XCAL
01h
1Dh
R/W
OTP
XCAL<7>
XCAL<6>
XCAL<5>
XCAL<4>
XCAL<3>
XCAL<2>
XCAL<1>
XCAL<0>
YCAL
01h
1Eh
R/W
OTP
YCAL<7>
YCAL<6>
YCAL<5>
YCAL<4>
YCAL<3>
YCAL<2>
YCAL<1>
YCAL<0>
ZCAL
01h
1Fh
R/W
OTP
ZCAL<7>
ZCAL<6>
ZCAL<5>
ZCAL<4>
ZCAL<3>
ZCAL<2>
ZCAL<1>
ZCAL<0>
Offset_cal<7:0>: This offset is in 2s compliment format and is added to the
output value. Digital calibration resolution can be selected via CALRES1 and
CALRES0 bits in OUT_CNTL register.