TCA6408ARSVR datasheet(22/50 Pages) TI2

22 / 50 page

SCL

SDA

MSB

Bit

LSB

Byte: 1010 1010 ( 0xAAh )

SDA line stable while SCL line is high

ACK

Figure 8-4. Bit Transfer

Table 8-2. Interface Definition

BYTE

BIT

7 (MSB)

0 (LSB)

I2C target address

ADDR

R/ W

I/O data bus

8.5.2 Bus Transactions

Data must be sent to and received from the target devices, and this is accomplished by reading from or writing to

registers in the target device.

Registers are locations in the memory of the target which contain information, whether it be the configuration

information or some sampled data to send back to the controller. The controller must write information to these

registers in order to instruct the target device to perform a task.

While it is common to have registers in I2C targets, note that not all target devices will have registers. Some

devices are simple and contain only 1 register, which may be written to directly by sending the register data

immediately after the target address, instead of addressing a register. An example of a single-register device

would be an 8-bit I2C switch, which is controlled via I2C commands. Since it has 1 bit to enable or disable

a channel, there is only 1 register needed, and the controller merely writes the register data after the target

address, skipping the register number.

8.5.2.1 Writes

To write on the I2C bus, the controller will send a START condition on the bus with the address of the target,

as well as the last bit (the R/ W bit) set to 0, which signifies a write. After the target sends the acknowledge

bit, the controller will then send the register address of the register to which it wishes to write. The target will

acknowledge again, letting the controller know it is ready. After this, the controller will start sending the register

data to the target until the controller has sent all the data necessary (which is sometimes only a single byte), and

the controller will terminate the transmission with a STOP condition.

Figure 8-5 shows an example of writing a single byte to a target register.

TCA6408A

SCPS192E – APRIL 2009 – REVISED JANUARY 2023

www.ti.com

Submit Document Feedback

Product Folder Links: TCA6408A

TCA6408ARSVR Scheda tecnica(PDF) 22 Page - Texas Instruments

TCA6408ARSVR Scheda tecnica(HTML) 22 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

Scheda tecnica Scarica

Link URL