TCA9539_15 Datasheet, PDF (22/42 Pages) Texas Instruments – Low Voltage 16-Bit I2C and SMBus Low-Power I/O Expander

TCA9539
SCPS202B – OCTOBER 2009 – REVISED OCTOBER 2015
www.ti.com
8.6.3.1.1 Writes
To write on the I²C bus, the master will send 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
will then send the register address of the register to which it wishes to write. The slave will acknowledge again,
letting the master know it is ready. After this, the master will start 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 will terminate the
transmission with a STOP condition.
See Register Descriptions section to see list of the TCA9539's 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 1 1 1 0 1 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
<br/>
Master controls SDA line
Slave controls SDA line
Device (Slave) Address (7 bits)
Register Address 0x01 (8 bits) Data Byte to Register 0x01 (8 bits)
S 1 1 1 0 1 A1 A0 0 A 0 0 0 0 0 1 0 0 A D7 D6 D5 D4 D3 D2 D1 D0 A P
START
R/W=0 ACK
ACK
Figure 29. Write to the Polarity Inversion Register
ACK STOP
22
Submit Documentation Feedback
Product Folder Links: TCA9539
Copyright © 2009–2015, Texas Instruments Incorporated