SCL

SDA

Data to

Register

Start Condition

R/W

ACK From Slave

ACK From Slave

ACK From Slave

1

9

8

7

6

5

4

3

2

Data

1/0

0

1

1

S

0

1

A1 A0 0

A

1

0

0

0

0

0

0

A

A

P

Data to Register

Command Byte

Slave Address

SCL

Start Condition

Data 1 Valid

SDA

Write to Port

Data Out

From Port

R/W ACK From Slave

ACK From Slave

ACK From Slave

1

9

8

7

6

5

4

3

2

Data 1

1

0

1

1

S

0

1

A1 A0 0

A

0

0

0

0

0

0

0

A

A

P

tpv

Data to Port

Command Byte

Slave Address

21

TCA9538

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SCPS199D – AUGUST 2014 – REVISED OCTOBER 2016

Product Folder Links: TCA9538

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8.6.3.1 Bus Transactions

Data is exchanged between the master and the TCA9538 through write and read commands.

8.6.3.1.1

Writes

Data is transmitted to the TCA9538 by sending the device address and setting the least-significant bit (LSB) to a

logic 0 (see Figure 18 for device address). The command byte is sent after the address and determines which

register receives the data that follows the command byte (see Figure 20 and Figure 21). There is no limitation on

the number of data bytes sent in one write transmission.

Figure 20. Write to Output Port Register

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Figure 21. Write to Configuration or Polarity Inversion Registers