TCA8418E_15 Datasheet, PDF (23/50 Pages) Texas Instruments – I2C Controlled Keypad Scan IC With Integrated ESD Protection

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TCA8418E
SCPS222C – MAY 2010 – REVISED OCTOBER 2015
Programming (continued)
8.5.2.1 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.
Figure 24 shows an example of writing a single byte to a 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 1 0 1 0 0 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 24. Write to Register
ACK STOP
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 0 1 1 0 1 0 0 0 A 0 0 0 0 0 0 0 1 A D7 D6 D5 D4 D3 D2 D1 D0 A P
START
R/W=0 ACK
ACK
Figure 25. Write to Configuration Register
ACK STOP
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