Cirrus-logic CS53L21 User Manual download pdf (Page 35)

DS700PP1 35

CS53L21

increment bit in MAP allows successive reads or writes of consecutive registers. Each byte is separated

by an acknowledge bit. The ACK bit is output from the CS53L21 after each input byte is read and is input

to the CS53L21 from the microcontroller after each transmitted byte.

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

in Figure 20, 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 100101x0 (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 100101x1 (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

ACKACKACK

1 0 0 1 0 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 1910 11 13 14 15 27 28

DATA +n

Figure 19. Control Port Timing, I²C Write

SCL

CHIP ADDRESS (WRITE)

MAP BYTE

DATA

DATA +1

START

ACK

STOP

ACK

1 0 0 1 0 1 AD0 0

SDA

1 0 0 1 0 1 AD0 1

CHIP ADDRESS (READ)

START

INCR 6 5 4 3 2 1 0

7 0 7 0 7 0

168 9 12 13 14 154 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 20. Control Port Timing, I²C Read

1 2 ... 30 31 32 33 34 35 36 37 38 39 40 ... 65 66

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Cirrus-logic CS53L21 User Manual Page 35

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