Renesas rl78 User Manual
RL78/G1A
CHAPTER 13 SERIAL INTERFACE IICA
Figure 13-27. Communication Reservation Protocol
DI
SET1 STT0
Define communication
reservation
reservation
Wait
MSTS0 = 0?
(Communication reservation)
Note 2
Yes
No
(Generate start condition)
Cancel communication
reservation
reservation
MOV IICA0, #
××H
EI
Sets STT0 flag (communication reservation)
Defines that communication reservation is in effect
(defines and sets user flag to any part of RAM)
(defines and sets user flag to any part of RAM)
Secures wait time
Note 1
by software.
Confirmation of communication reservation
Clear user flag
IICA0 write operation
Notes 1. The wait time (f
MCK
) is calculated as follows.
(IICWL0 setting value + IICWH0 setting value + 4) + t
F
× 2 × f
MCK
[clocks]
2. The communication reservation operation executes a write to the IICA shift register 0 (IICA0) when a
stop condition interrupt request occurs.
Remark STT0: Bit 1 of IICA control register 00 (IICCTL00)
MSTS0: Bit 7 of IICA status register 0 (IICS0)
IICA0: IICA shift register 0
IICWL0: IICA low-level width setting register 0
IICWH0:
IICA high-level width setting register 0
t
F
:
SDAA0 and SCLA0 signal falling times
f
MCK
:
IICA operation clock frequency
R01UH0305EJ0200 Rev.2.00
606
Jul 04, 2013