MC81F4332 Datasheet, PDF (164/198 Pages) Finechips – ABOV SEMICONDUCTOR 8-BIT SINGLE-CHIP MICROCONTROLLERS

MC81F4x16
Read = read/write bit is 1 = data is transferred from slave to master.
After each data bytes are transferred, ACK can be transferred from receiver. But meaning is different
based on situation.
- Write time : master transmit and slave receive,
slave transmit a ACK when one byte data is correctly received.
So, slave must transmit a ACK when receive is finished.
- Read time : slave transmit and slave receive,
master transmit a ACK when there are more bytes to transmit.
So, if there is no more data to transmit, master dose not transmit a ACK.
1 Bit Transmit
Figure 25-3 Acknowledge on the IIC-BUS
Figure 25-4 Bit transfer on the IIC-BUS
The data bytes and ACK are consist of one bit transmits. If SDA is not changed while SCL is staying
high, SDA status is one bit data. As already said, If SDA is changed while SCL is staying high, it is
START or STOP condition. Therefore, transfer device change the SDA status while SCL is staying
low. And when SCL is going to low, 1 bit transmit is finished.
1 bit data value and state are,
1 : high state ( more preciously said, line is open-drained and pulled up ).
0 : low state
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October 19, 2009 Ver.1.35