CHAPTER 16 I
2
C BUS
User’s Manual U16896EJ2V0UD
515
16.14 Cautions
(1) When IICF0.STCEN0 bit = 0
Immediately after I
2
C0 operation is enabled, the bus communication status (IICF0.IICBSY0 bit = 1) is
recognized regardless of the actual bus status. To execute master communication in the status where a stop
condition has not been detected, generate a stop condition and then release the bus before starting the master
communication.
Use the following sequence for generating a stop condition.
<1> Set the IICCL0 register.
<2> Set the IICC0.IICE0 bit.
<3> Set the IICC0.SPT0 bit.
(2) When IICF0.STCEN0 bit = 1
Immediately after I
2
C0 operation is enabled, the bus released status (IICBSY0 bit = 0) is recognized regardless
of the actual bus status. To generate the first start condition (IICC0.STT0 bit = 1), it is necessary to confirm
that the bus has been released, so as to not disturb other communications.
(3) When the IICC0.IICE0 bit of the V850ES/KE1+ is set to 1 while communications with other devices are in
progress, the start condition may be detected depending on the status of the communication line. Be sure to
set the IICC0.IICE0 bit to 1 when the SCL0 and SDA0 lines are high level.
(4) Determine the operation clock frequency by the IICCL0 and IICX0 registers before enabling the operation
(IICC0.IICE0 bit = 1). To change the operation clock frequency, clear the IICC0.IICE0 bit to 0 once.
(5) After the IICC0.STT0 and IICC0.SPT0 bits have been set to 1, they must not be re-set without being cleared to
0 first.
(6) If transmission has been reserved, set the IICC0.SPIE0 bit to 1 so that an interrupt request is generated by the
detection of a stop condition. After an interrupt request has been generated, the wait state will be released by
writing communication data to I
2
C0, then transferring will begin. If an interrupt is not generated by the detection
of a stop condition, transmission will halt in the wait state because an interrupt request was not generated.
However, it is not necessary to set the SPIE0 bit to 1 for the software to detect the IICS0.MSTS0 bit.
<R>
<R>
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