21

Example: Polling of Status register (X-Y Motion Bit and Button bits)

To poll the STATUS register, the following structure can be used:

1

2

DA

RA

START

0000010

1010111

7

7

0

0

00

ADBS

Address 0 x 57

Register

Address 0 x 02

ACK

ACK

R/W

ai

Packet

number

Packet

type

SDA

host

SDA

ADBS

3

4

DA

DP

5

DP

START

ACK

NAK

STOP

ACK

00010001

1010111

R/W

70

00000000

Host could

also drive

another

START

condition

instead of a

STOP

condition

Packet

number

Packet

type

SDA

host

SDA

ADBS

ADBS Address

0 x 57

ADBS

STATUS

register

ADBS

STATUS

register

70

1

Figure 19. TWI polling

In this case, the host read ADBM-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

PixArt Imaging Inc.

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PixArt Imaging Inc.