Datasheet
RL78/L12    CHAPTER 13 SERIAL INTERFACE IICA 
R01UH0330EJ0200 Rev.2.00      561 
Dec 13, 2013 
Figure 13-29. Master Operation in Multi-Master System (2/3) 
STT0 = 1
Wait
Slave operation
Yes
MSTS0 = 1?
EXC0 = 1 or COI0 =1?
Prepares for starting communication 
(generates a start condition).
Secure wait time
Note
 by software. 
Waits for bus release 
(communication being reserved).
Wait state after stop condition 
was detected and start condition 
was generated by the communication 
reservation function.
No
INTIICA0
interrupt occurs?
Yes
Yes
No
No
A
C
STT0 = 1
Wait
Note
Slave operation
Yes
IICBSY0 = 0?
EXC0 = 1 or COI0 =1?
Prepares for starting communication 
(generates a start condition).
Disables reserving communication.
Enables reserving communication.
Waits for bus release 
Detects a stop condition.
No
No
INTIICA0
interrupt occurs?
Yes
Yes
No
Yes
STCF0 = 0?
No
B
D
C
D
Communication processing Communication processing
Note  The wait time is calculated as follows. 
  (IICWL0 setting value + IICWH0 setting value + 4) × fCLK + tF × 2 [clocks] 
Remark  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
CLK:  CPU/peripheral hardware clock frequency 










