I²C bus interface

STCF06

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8.3

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. One data bit is transferred during each clock

pulse. The data on the SDA line must remain stable during the HIGH period of the clock

pulse. Any change in the SDA line at this time will be interpreted as a control signal.

8.4

Acknowledge

The master (µP) puts a resistive HIGH level on the SDA line during the acknowledge clock

pulse (see Figure 7). The peripheral (STCF06) that acknowledges has to pull-down (LOW)

the SDA line during the acknowledge clock pulse, so that the SDA line is stable LOW during

this clock pulse. The peripheral which has been addressed has to generate an acknowledge

pulse after the reception of each byte, otherwise the SDA line remains at the HIGH level

during the ninth clock pulse duration. In this case, the master transmitter can generate the

STOP information in order to abort the transfer.

Figure 6.

Bit transfer

Figure 7.

Acknowledge on I²C bus