AN1146 STMicroelectronics, AN1146 Datasheet - Page 6

• Manufacturer Part Number: AN1146
• Description: I2C COMMUNICATION BETWEEN ST52X301 AND EEPROM
• Manufacturer: STMicroelectronics

AN1146 - APPLICATION NOTE
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4.1.4 ‘Ack’ block
After sending 8 bits data, ST52x301 releases the SDA bus, setting the pin P0 in input. REG_CONF0 is
used to set each pin of the parallel port in input or in output.
During the 9-th clock pulse period, the EEPROM pulls the SDA bus low to acknowledge reception of the
data byte: the byte read onto ST52x301 parallel port is stored into an ‘ ack ’ variable (‘ read_ack1’ block).
To understand if the LSB is 0 (on P0), therefore if the EEPROM has correctly received the data, the 8
bit variable ‘ ack ’ is masked. If P0 bit results to be 1, an error has occurred and the communication is
restarted.
Fig. 8 - Acknowledgement Block