NEC 78K0 Series User Manual page 441

(5) Setting STT0 and SPT0 (bits 1 and 0 of IICC0) again after they are set and before they are cleared to 0 is
prohibited.
(6) When transmission is reserved, set SPIE0 (bit 4 of IICL0) to 1 so that an interrupt request is generated
when the stop condition is detected. Transfer is started when communication data is written to IIC0
after the interrupt request is generated. Unless the interrupt is generated when the stop condition is
detected, the device stops in the wait state because the interrupt request is not generated when
communication is started. However, it is not necessary to set SPIE0 to 1 when MSTS0 (bit 7 of IICS0) is
detected by software.
CHAPTER 17 SERIAL INTERFACE IIC0
Preliminary User's Manual U17260EJ3V1UD
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