Panasonic MN101C77C User Manual

Chapter 12    Serial Interface 3

Operation

XII - 10

This LSI contains a serial interface 3 that can be used for both communication types of clock synchronous

and single master IIC.

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Activation Factor for Communication

Table 12-3-1 shows the activation factor for communication. At master communication, the transfer clock is

generated by setting data to the transmit/receive shift register SC3TRB, or by receiving start condition. The

input signal from the SBT3 pin is masked inside of serial interface to prevent errors by noise except during

communication. This mask is automatically released by setting data to SC3TRB (writing data to the

SC3TRB register), or by inputting start condition to the data input pin. Therefore, at slave, input the external

clock after setting data to SC3TRB, or by inputting start condition.

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Transfer Bit Count Setup

The transfer bit count can be selected from 1 bit to 8 bits. Set it by the SC3LNG 2 to 0 flag of the SC3MD0

register (at reset : 111). The SC3LNG2 to 0 flag holds the previous set values till it is set again.

The SBT3 pin is masked inside serial to prevent errors by noise. At slave, input clock to the

SBT3 pin after start condition is input or data is set to SC3TRB.

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Start Condition Setup

Start condition can be selected if it is enabled or not. Set by the SC3STE flag of the SC3MD0 register.

When start condition is enabled. the transfer bit counter is cleared as start condition is input during

communication, and after that, the communication is automatically started again. Start condition is en-

abled as data line (the SBI3 pin (with 3 channels) or the SBO3 pin (with 2  channels)) is changed from "H"

to "L", when clock line (the SBT3 pin) is "H".

transmission

reception

Set dummy data

Input start condition

Input clock 

after dummy data is set

Input clock 

after start condition is input

Activation factor

Input clock after

transmission data is set

Set transmission data

at slave

at master