CS2000-CP

26

DS761F1

Since the read operation cannot set the MAP, an aborted write operation is used as a preamble. As shown

in Figure 22, the write operation is aborted after the acknowledge for the MAP byte by sending a stop con-

dition. The following pseudocode illustrates an aborted write operation followed by a read operation.

Send start condition.

Send 100111x0 (chip address & write operation).

Receive acknowledge bit.

Send MAP byte, auto increment off.

Receive acknowledge bit.

Send stop condition, aborting write.

Send start condition.

Send 100111x1(chip address & read operation).

Receive acknowledge bit.

Receive byte, contents of selected register.

Send acknowledge bit.

Send stop condition.

Setting the auto increment bit in the MAP allows successive reads or writes of consecutive registers. Each

byte is separated by an acknowledge bit.

4

5

6

7

24 25

SCL

CHIP ADDRESS (WRITE)

MAP BYTE

DATA

DATA +1

START

ACK

STOP

ACK

ACK

ACK

1

0

0

1

1

1

AD0

0

SDA

INCR

6

5

4

3

2

1

0

7

6

1

0

7

6

1

0

7

6

1

0

0

1

2

3

8

9

12

16 17 18

19

10 11

13 14 15

27 28

26

DATA +n

Figure 22. Control Port Timing, I²C Write

SCL

CHIP ADDRESS (WRITE)

MAP BYTE

DATA

DATA +1

START

ACK

STOP

ACK

ACK

ACK

1

0

0

1

1 1 AD0 0

SDA

1

0

0

1

1

1 AD0 1

CHIP ADDRESS (READ)

START

INCR

6

5

4

3

2

1

0

7

0

7

0

7

0

NO

16

8

9

12 13 14 15

4

5

6

7

0

1

20 21 22 23 24

26 27 28

2

3

10 11

17 18

19

25

ACK

DATA + n

STOP

Figure 23. Control Port Timing, I²C Aborted Write + Read