TDA7437N Datasheet, PDF (7/23 Pages) STMicroelectronics – DIGITALLY CONTROLLED AUDIO PROCESSOR

TDA7437N
I²C BUS INTERFACE
Data transmission from microprocessor to the TDA7437N and viceversa takes place thru the 2 wires I²C BUS
interface, consisting of the two lines SDA and SCL (pull-up resistors to positive supply voltage must be exter-
nally connected).
Data Validity
As shown in fig. 1, 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.
Start and Stop Conditions
As shown in fig. 2 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.A STOP conditions must be sent before
each START condition.
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.
Acknowledge
The master (µP) puts a resistive HIGH level on the SDA line during the acknowledge clock pulse (see fig. 3).
The peripheral (audioprocessor) that acknowledges has to pull-down (LOW) the SDA line during the acknowl-
edge clock pulse, so that the SDA line is stable LOW during this clock pulse.The audioprocessor which has been
addressed has to generate an acknowledge after the reception of each byte, otherwise the SDA line remains at
the HIGH level during the ninth clock pulse time. In this case the master transmitter can generate the STOP
information in order to abort the transfer.
Transmission without Acknowledge
Avoiding to detect the acknowledge of the audioprocessor, the µP can use a simplier transmission: simply it
waits one clock without checking the slave acknowledging, and sends the new data.This approach of course is
less protected from misworking and decreases the noise immunity.
Figure 1. Data Validity on the I²CBUS
SDA
SCL
DATA LINE
STABLE, DATA
VALID
CHANGE
DATA
ALLOWED
Figure 2. Timing Diagram of I²CBUS
D99AU1031
SCL
SDA
START
Figure 3. Acknowledge on the I²CBUS
D99AU1032
I²CBUS
STOP
SCL
1
2
3
7
8
9
SDA
START
MSB
D99AU1033
ACKNOWLEDGMENT
FROM RECEIVER
7/23