NEC V850/SA1 mPD703015 Preliminary User's Manual

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NEC V850/SA1 mPD703015 Preliminary User's Manual Manual pdf 263 page image

CHAPTER 10 SERIAL INTERFACE FUNCTION26310.3.10 ArbitrationWhen several master devices simultaneously output a start condition (when STT is set to 1 before STD is set to1Note), communication among the master devices is performed as the number of clocks are adjusted until the datadiffers. This kind of operation is called arbitration.When one of the master devices loses in arbitration, an arbitration loss flag (ALD) in the IIC status register (IICS0)is set via the timing by which the arbitration loss occurred, and the SCL and SDA lines are both set for highimpedance, which releases the bus.The arbitration loss is detected based on the timing of the next interrupt request (the eighth or ninth clock, when astop condition is detected, etc.) and the ALD = 1 setting that has been made by software.For details of interrupt request timing, see “10.3.5 I 2C interrupt requests (INTIIC0)”.Note STD : Bit 1 of IIC status register (IICS0)STT : Bit 1 of IIC control register (IICC0)