PixArt Imaging Inc.
ADBS-A350 Optical Finger Navigation
Example: Polling of Status register (X-Y Motion Bit and Button bits)
To poll the STATUS register, the following structure can be used:
ADBS
Address 0 x 57
Register
Address 0 x 02
Packet
number
1
2
Packet
type
DA
RA
0
7
0
0
7
0
SDA
START 1010111
0000010
host
R/W
ai
SDA
ADBS
ACK
ACK
ADBS
STATUS
register
ADBS
STATUS
register
ADBS Address
0 x 57
Packet
3
4
5
number
Host could
also drive
another
START
condition
instead of a
STOP
Packet
type
DA
DP
DP
SDA
START 1010111
1
ACK
NAK STOP
host
R/W
7
0
7
0
SDA
ADBS
condition
ACK
00000000
00010001
Figure 24. TWI polling
In this case, the host read ADBS-A350 data packets until the update bit (bit 4). Then the host could read successive
registers using the ai bit example below.
Note: polling the Status register rather than using the DATA_RDY pin increases power consumption
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PixArt Imaging Inc.
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24
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