Start Condition Duplicate Protect Function; Stop Condition Generation Method - Renesas M16C FAMILY series Hardware Manual

M 1 6 C 2 / 8 G o r u p ( M 1 6 C

16.10 START Condition Duplicate Protect Function

A START condition is generated when verifying that the BB flag in the S10 register does not use buses.
However, if the BB flag is set to "1" (bus busy) by the START condition which other master device gener-
ates immediately after the BB flag is verified, the START condition is suspended by the START condition
duplicate protect function. When the START condition duplicate protect function starts, it operates as fol-
lows:
•Disable the start condition standby setting
If the function has already been set, first exit START condition standby mode and then set the MST and
TRX bits in the S10 register to "0".
•Writing to the S00 register is disabled. (The START condition trigger generation is disabled)
•If the START condition generation is interrupted, the AL flag in the S10 register becomes "1".(arbitration
lost detection)
The START condition duplicate protect function is valid between the SDA falling edge of the START condi-
tion and the receive completion of the slave address. Figure 16.15 shows the duration of the START
condition duplicate protect function.
S
CL
S
DA
BB flag
Figure 16.15 The duration of the start condition duplicate protect function

16.11 STOP Condition Generation Method

When the ES0 bit in the S1D0 register is set to "1" (I
the S10 register are set to "1" at the same time, set the BB flag, PIN bit and 4 low-order bits in the S10
register to "0" simultaneously, to enter STOP condition standby mode. When dummy data is written to the
S00 register next, the STOP condition is generated. The STOP condition generation timing varies between
standard clock mode and high-speed clock mode. See Figure 16.17 and Table 16.8.
Until the BB flag in the S10 register becomes "0" (bus free) after an instruction to generate the STOP
condition is executed, do not write data to the S10 and S00 registers. Otherwise, the STOP condition
waveform may not be generated correctly.
If an input signal level of the S
is executed, a signal level of the S
outputs an "L" signal to S
In that case, the MCU can stop an "L" signal output to the S
0 to the ES0 bit in the S1D0 register (disabled), or writing 1 to the IHR bit in the S1D0 register (reset
release).
R e . v 2 0 . 0 J a . n 3 , 1 2 0 0 7
R E J 0 9 B 0 0 4 7 0 - 2 0 0
2 / , 8 M 1 6 C 2 / 8 ) B
1 clock
1 bit 2 bit
The duration of start condition duplicate protect
pin is set to low ("L") after the instruction to generate the STOP condition
CL
pin becomes high ("H"), and the BB flag is set to 0 (bus free), the MCU
CL
pin.
CL
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f o 3 8 5
16. MULTI-MASTER I
2 clock 3 clock
3 bit
2
C bus interface enabled) and the MST and TRX bits in
pin by generating the STOP condition, writing
CL
2
C bus INTERFACE
ACK clock
8 clock
8 bit ACK bit