TCA9538 Datasheet, PDF (21/37 Pages) Texas Instruments – Low Voltage 8-Bit I2C and SMBus Low-Power I/O Expander

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TCA9538
SCPS199C – AUGUST 2014 – REVISED OCTOBER 2015
8.6.3.1 Bus Transactions
Data is exchanged between the master and 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.
SCL
12 345 678 9
Slave Address
Command Byte
Data to Port
SDA S 1 1 1 0 0 A1 A0 0 A 0 0 0 0 0 0 0 1 A
Data 1
AP
Start Condition
Write to Port
R/W ACK From Slave
ACK From Slave
ACK From Slave
Data Out
From Port
Figure 20. Write to Output Port Register
Data 1 Valid
t_pv
<br/>
SCL 1 2 3 4 5 6 7 8 9
Slave Address
Command Byte
Data to Register
SDA _{S 1 1 1 0 0 A1 A0 0 A 0 0 0 0 0 0 1 1/0 A}
Data
Start Condition
R/W ACK From Slave
ACK From Slave
Data to
Register
Figure 21. Write to Configuration or Polarity Inversion Registers
AP
ACK From Slave
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