CS35L32 datasheet(31/51 Pages) CIRRUS

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DS963F5

CS35L32

4.14 Control Port Operation

Figure 4-11. Control-Port Timing—I2C Writes with Autoincrement

The logic state of FLOUT2/AD0 configures the I²C device address upon a device power up, after RESET has been

deasserted. The bit labeled AD0 in the address byte in Fig. 4-11 reflects the logic state of pin FLOUT2/AD0.

If the I²C operation is a write, the next byte is the memory address pointer (MAP); the 7 LSBs of the MAP byte select the

address of the register to be read or written to next. The MSB of the MAP byte, INCR, selects whether autoincrementing

is to be used (INCR = 1), allowing successive reads or writes of consecutive registers.

Each byte is separated by an acknowledge bit, ACK, which the CS35L32 outputs after each input byte is read and is input

to the CS35L32 from the microcontroller after each transmitted byte.

Also for writes, bytes following the MAP byte are written to the CS35L32 register addresses pointed to by the last received

MAP address plus however many autoincrements have occurred. Fig. 4-11 shows a write pattern with autoincrementing.

If the operation is a read, the contents of the register pointed to by the last received MAP address plus however many

autoincrements have occurred, are output in the next byte. Fig. 4-12 shows a read pattern following the write pattern in

Fig. 4-11. Notice how read addresses are based on the MAP byte from Fig. 4-11.

Figure 4-12. Control-Port Timing—I²C Reads with AutoIncrement

If a read address different from that based on the last received MAP address is desired, an aborted write operation can

be used as a preamble that sets the desired read address. This preamble technique is shown in Fig. 4-11, in which a write

operation is aborted (after the ACK for the MAP byte) by sending a stop condition.

Figure 4-13. Control-Port Timing—I²C Reads with Preamble and Autoincrement

The following pseudocode illustrates an aborted write operation followed by a single read operation when the AD0 bit in

the slave address is 0. For multiple read operations, autoincrement would be set to ON (as shown in Fig. 4-13).

Send start condition.

Send 10000000 (chip address and write operation).

Receive acknowledge bit.

Send MAP byte, autoincrement off.

24 25

SCL

CHIP ADDRESS (WRITE)

MAP BYTE

DATA

START

STOP

ACK

SDA

16 17 18 19

10 11

13 14 15

27 28

DATA

SDA

Source

Master

Pullup

Slave

Master

Pullup

ACK

MAP Addr

Slave Address

Data to

Addr X+1

Data to

Addr X+n

Master

Slave

Data to

Addr X

SCL

DATA

STOP

ACK

SDA

CHIP ADDRESS (READ)

START

16 17

34 35 36

ACK

Slave Address

DATA

Data from

Addr X+n+1

Data from

Addr X+n+2

Data from

Addr X+n+3

SDA

Source

Master

Pullup

Slave

Master

Master Pullup

SCL

CHIP ADDRESS (WRITE)

MAP BYTE

DATA

START

ACK

STOP

ACK

SDA

CHIP ADDRESS (READ)

START

12 13 14 15

20 21 22 23 24

26 27 28

10 11

17 18 19

ACK

STOP

MAP Addr = Z

Slave Address

DATA

Data from

Addr Z

Data from

Addr Z+1

Data from

Addr Z+n

SDA

Source

Master

Pullup

Slave

Master

Pullup

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