TDA7546 Datasheet, PDF (25/68 Pages) STMicroelectronics – Multichip module for TMC tuner applications

TDA7546
Functional description
5.1.5
I²C-bus interface
The TDA7512F supports the I²C-Bus protocol. This protocol defines any device that sends
data onto the bus as a transmitter, and the receiving device as the receiver. The device that
controls the transfer is a master and device being controlled is the slave. The master will
always initiate data transfer and provide the clock to transmit or receive operations.
Data transition
Data transition on the SDA line must only occur when the clock SCL is LOW. SDA transitions
while SCL is HIGH will be interpreted as START or STOP condition.
Start condition
A start condition is defined by a HIGH to LOW transition of the SDA line while SCL is at a
stable HIGH level. This "START" condition must precede any command and initiate a data
transfer onto the bus.
The device continuously monitors the SDA and SCL lines for a valid START and will not
response to any command if this condition has not been met.
Stop condition
A STOP condition is defined by a LOW to HIGH transition of the SDA while the SCL line is at
a stable HIGH level. This condition terminates the communication between the devices and
forces the bus-interface of the device into the initial condition.
Acknowledge
Indicates a successful data transfer. The transmitter will release the bus after sending 8 bits
of data. During the 9th clock cycle the receiver will pull the SDA line to LOW level to indicate
it receive the eight bits of data.
Data transfer
During data transfer the device samples the SDA line on the leading edge of the SCL clock.
Therefore, for proper device operation the SDA line must be stable during the SCL LOW to
HIGH transition.
Device addressing
To start the communication between two devices, the bus master must initiate a start
instruction sequence, followed by an eight bit word corresponding to the address of the
device it is addressing.
The most significant 6 bits of the slave address are the device type identifier.
The TDA7512F device type is fixed as "110001".
The next significant bit is used to address a particular device of the previous defined type
connected to the bus.
The state of the hardwired PIN 41 defines the state of this address bit. So up to two devices
could be connected on the same bus. When PIN 41 is connected to VCC2 the address bit
“1” is selected. When PIN 41 is left open the address bit “0” is selected. Therefor a double
FM tuner concept is possible.
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