TDA7511

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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 trans-

mit 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 TDA 7511

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 TDA

7511 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 TDA 7511 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, fol-

lowed 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 TDA 7511 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. In this case the AM part

doesn’t work. Otherwise the address bit “0” is selected (FM and AM is working). Therefor a double FM tuner

concept is possible.

The last bit of the start instruction defines the type of operation to be performed:

- When set to "1", a read operation is selected

- When set to "0", a write operation is selected

The TDA 7511 connected to the bus will compare their own hardwired address with the slave address being

transmitted, after detecting a START condition. After this comparison, the TDA 7511 will generate an "acknowl-

edge" on the SDA line and will do either a read or a write operation according to the state of R/W bit.