PixArt Imaging Inc.
ADBS-A350 Optical Finger Navigation
Example: Multiple-Byte Read from Sensor Register using ‘ai’ bit
The ai is a useful feature, especially in the case of reading Delta_X, Delta_Y, and Delta_HI in succession once either the
DATA_RDY interrupt pin and/or update bit in the STATUS register bit are set.
Once the ai bit is set, the slave will deliver data packets from successive addresses until the ‘STOP’ condition from the
host.
In the example below, 3 bytes are read successively from registers 0x03, 0x04, and 0x05.
ADBS Address
0 x 57
Register Address
0 x 03
Packet
number
1
2
Packet
type
DA
RA
7
0
7
0
SDA
host
START 1010111 0
R/W
1
0000011
ai
SDA
ADBS
ACK
ACK
ADBS Data
from address
0 x 03
ADBS Data
from address
0 x 04
ADBS Data
from address
0 x 05
ADBS
Address 0 x 57
Packet
number
3
4
5
6
Host could
also drive
another
START
condition
instead of a
STOP
Packet
type
DA
DP
DP
DP
7
0
SDA
host
START 1010111 1
R/W
ACK
ACK
NAK STOP
7
0
7
0
SDA
ADBS
ACK
10101101
00000001
10000101
condition
Figure 25. TWI ai bit
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
25
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