TCA9534_16 Datasheet, PDF (20/38 Pages) Texas Instruments – Low Voltage 8-Bit I2C and SMBUS Low-Power I/O Expander with Interrupt Output and Configuration Registers

TCA9534
SCPS197B – SEPTEMBER 2014 – REVISED NOVEMBER 2016
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8.6.3.1 Bus Transactions
Data is exchanged between the master and the TCA9534 through write and read commands.
8.6.3.1.1 Writes
To write on the I²C bus, the master sends a START condition on the bus with the address of the slave, as well
as the last bit (the R/W bit) set to 0, which signifies a write. After the slave sends the acknowledge bit, the master
then sends the register address of the register to which it wishes to write. The slave acknowledges again, letting
the master know it is ready. After this, the master starts sending the register data to the slave until the master
has sent all the data necessary (which is sometimes only a single byte), and the master terminates the
transmission with a STOP condition.
See Table 3 to see list of the internal registers and a description of each one.
Figure 28 shows an example of writing a single byte to a slave register.
Master controls SDA line
Slave controls SDA line
Write to one register in a device
Device (Slave) Address (7 bits)
Register Address N (8 bits)
Data Byte to Register N (8 bits)
S 0 1 0 0 A2 A1 A0 0 A B7 B6 B5 B4 B3 B2 B1 B0 A D7 D6 D5 D4 D3 D2 D1 D0 A P
START
R/W=0 ACK
ACK
Figure 28. Write to Register
ACK STOP
Figure 29 shows an example of writing to the output port register.
SCL
12346 78 9
Slave Address
Command Byte
Data to Register
SDA S 0 1 0 0 A2 A1 A0 0 A 0 0 0 0 0 0 0 1 A
Data 1
AP
Start Condition
Write to
Port
Data Out
From Port
R/W ACK From Slave
ACK From Slave
ACK From Slave
tpv
Figure 29. Write to Output Port Register
Data 1 Valid
Figure 30 shows an example of writing to the configuration or polarity inversion registers.
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