RL78/G1H CHAPTER 15 SERIAL INTERFACE IICA
R01UH0575EJ0120 Rev. 1.20 Page 467 of 920
Dec 22, 2016
Figure 15 - 33 shows the Communication Reservation Protocol.
Figure 15 - 33 Communication Reservation Protocol
Note 1. The wait time is calculated as follows.
(IICWLn setting value + IICWHn setting value + 4) + t
F × 2 × fMCK: [clocks]
Note 2. The communication reservation operation executes a write to the IICA shift register n (IICAn) when a stop condition
interrupt request occurs.
Remark1. STTn: Bit 1 of IICA control register n0 (IICCTLn0)
MSTSn: Bit 7 of IICA status register n (IICSn)
IICAn: IICA shift register n
IICWLn: IICA low-level width setting register n
IICWHn: IICA high-level width setting register n
t
F: SDAAn and SCLAn signal falling times
f
MCK: IICA operating clock frequency
Remark2. n = 0, 1
DI
SET1 STTn
Define communication
reservation
Wait
Cancel communication
reservation
EI
MSTSn = 0?
(Communication reservation)
Note 2
Yes
No
(Generate start condition)
MOV IICAn, #xxH
Sets STTn flag (communication reservation)
Defines that communication reservation is in effect
(defines and sets user flag to any part of RAM )
Secures wait time
Note 1
by software.
Confirmation of communication reservation
Clear user flag
IICAn write operation
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