
CHAPTER 19 I
2
C BUS
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User’s Manual U16890EJ1V0UD
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STT0
Start condition trigger
0
Do not generate a start condition.
1
When bus is released (in STOP mode):
Generate a start condition (for starting as master). The SDA0 line is changed from high level to low level
and then the start condition is generated. Next, after the rated amount of time has elapsed, the SCL0
line is changed to low level.
When a third party is communicating
When communication reservation function is enabled (IICF0.IICRSV0 bit = 0)
Functions as the start condition reservation flag. When set to 1, automatically generates a start
condition after the bus is released.
When communication reservation function is disabled (IICRSV0 bit = 1)
The IICF0.STCF0 bit is set to 1. No start condition is generated.
In the wait state (when master device):
Generates a restart condition after releasing the wait.
Cautions concerning set timing
For master reception:
Cannot be set to 1 during transfer. Can be set to 1 only when the ACKE0 bit has been
cleared to 0 and slave has been notified of final reception.
For master transmission: A start condition cannot be generated normally during the ACK0 period. Set to 1 during the
wait period.
Cannot be set to 1 at the same time as the SPT0 bit.
Condition for clearing (STT0 bit = 0)
Note
Condition for setting (STT0 bit = 1)
Cleared by loss in arbitration
Cleared after start condition is generated by master
device
When the LREL0 bit = 1 (exit from communications)
When the IICE0 bit = 0 (operation stop)
Reset
Set by instruction
Note
This flag’s signal is invalid when the IICE0 bit = 0.
Remark
The STT0 bit is 0 if it is read after data setting.