TDA7801 datasheet(35/48 Pages) STMICROELECTRONICS

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TDA7801

I2C bus interface

8.1

Writing procedure

There are two possible procedures:

without increment: the I bit is set to 0 and the register is addressed by the subaddress.

Only this register is written by the data following the subaddress byte.

with increment: the I bit is set to 1 and the first register written is the one addressed by

subaddress. Then all the registers starting from the one indicated by this address up to

stop bit (or up to last register) are written.

8.2

Reading procedure

There are two possible procedures:

without increment: the I bit is set to 0 and the register is addressed by the subaddress

sent in the previous write procedure. Only this register is read by the data following the

address.

with increment: the I bit is set to 1 and the first register read is the one addressed by

subaddress sent in the previous write procedure. Then all registers starting from the

one indicated by this address up to stop bit (or up to last register) are read.

Note:

the reading procedure reset the register that has been read.

8.3

Data validity

The data on the SDA line must be stable during the high period of the clock. The high and

low state of the data line can only change when the clock signal on the SCL line is low.

8.4

Start and stop conditions

A start condition is a high to low transition of the SDA line while SCL is high.

The stop condition is a low to high transition of the SDA line while SCL is high.

8.5

Byte format

Every byte transferred to the SDA line must contain 8 bits. Each byte must be followed by an

acknowledge bit. The MSB is transferred first.

8.6

Acknowledge

The transmitter* puts a resistive HIGH level on the SDA line during the acknowledge clock

pulse. The receiver** has to pull-down the SDA line during the acknowledge clock pulse, so

that the SDA line is stable low using this clock pulse.

* Transmitter

= master (µP) when it writes an address to the TDA7801

= slave (TDA7801) when the µP reads a data byte from TDA7801

** Receiver

= slave (TDA7801) when the µP writes an address to the TDA7801

= master (µP) when it reads a data byte from TDA7801

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