UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 488

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

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(2) When communication reservation function is disabled (bit 0 (IICRSV) of IIC flag register 0 (IICF0) = 1)
(Communication reservation)
Note The communication reservation operation executes a write to IIC shift register 0 (IIC0) when a stop
Remark
When bit 1 (STT0) of IIC control register 0 (IICC0) is set to 1 when the bus is not used in a communication
during bus communication, this request is rejected and a start condition is not generated. The following two
statuses are included in the status where bus is not used.
To confirm whether the start condition was generated or request was rejected, check STCF (bit 7 of IICF0).
The time shown in Table 14-7 is required until STCF is set to 1 after setting STT0 = 1. Therefore, secure the
time by software.
When arbitration results in neither master nor slave operation
When an extension code is received and slave operation is disabled (ACK is not returned and the bus was
released when bit 6 (LREL0) of IICC0 was set to 1)
condition interrupt request occurs.
STT0:
MSTS0: Bit 7 of IIC status register 0 (IICS0)
IIC0:
Bit 1 of IIC control register 0 (IICC0)
IIC shift register 0
Yes
Note
Figure 14-22. Communication Reservation Protocol
Cancel communication
reservation
Define communication
reservation
CHAPTER 14 SERIAL INTERFACE IIC0
MOV IIC0, #
MSTS0 = 0?
Preliminary User’s Manual U19748EJ1V0UD
SET1 STT0
Wait
DI
EI
(Generate start condition)
No
H
Sets STT0 flag (communication reservation)
Defines that communication reservation is in effect
(defines and sets user flag to any part of RAM)
Secures wait period set by software (see Table 14-6).
Confirmation of communication reservation
Clear user flag
IIC0 write operation