RL78/G15 CHAPTER 13 SERIAL INTERFACE IICA
R01UH0959EJ0110 Rev.1.10 Page 557 of 765
Mar 7, 2023
(2) Master operation in multi-master system
Figure 13-28. Master operation in Multi-master System (1/3)
Release serial interface IICA0 from the reset state
and start clock supply.
START
Set the PER0 register
Set the port
IICWL0, IICWH0 ← xxH
SVA0 ← xxH
IICF0 ← 0xH
Set STCEN0 and IICRSV0
Set IICCTL01
IICCTL00 ← 0xx111xxB
ACKE0 = WTIM0 = SPIE0 = 1
IICCTL00 ← 1xx111xxB
IICE0 = 1
Set the port
INTIICA0 interrupt
occurred?
SPD0 = 1?
Start master operation?
IICRSV0 = 0?
Setting of the port multiplexed with the pin to be used
First, set the port to input mode and the output latch to 0
(see 13.3.8 Registers controlling port functions of IICA serial input/output pins).
Set the transfer clock
Set the local address
Set the start condition
Set the port from input mode to output mode and enable the output of the I
2
C bus
(see 13.3.8 Registers controlling port functions of IICA serial input/output pins).
Yes
INTIICA0 interrupt
occurred?
Yes
No
No
SPIE0 = 0
SPT0 = 1
Wait for communication Initial settings
The bus state is
being checked
Check the bus state
Note 1
STCEN0 = 1?
The bus is released for
a certain period
SPD0 = 1?
Yes
No
Slave operation
INTIICA0 interrupt
occurred?
Yes
Yes
No
Slave operation
Wait for detection of the stop
condition
Prepare for starting communication
(generate a stop condition)
Wait for specification of the slave by the other master
Wait for a communication start request (user program dependent)
No
(No communication
start request)
Yes
(Communication start request)
Slave operation
SPIE0 = 1
No
A B
Yes
Enable
communication
reservation
Disable
communication
reservation
No
Wait for a communication request
Yes
No
1
Note 1. Confirm that the bus is released (CLD0 bit = 1, DAD0 bit = 1) for a certain period (for example, for a period of
one frame). If the SDAA0 pin is constantly at the low level, decide whether to release the I
2
C bus (SCLA0 and
SDAA0 pins = high level) in conformance with the specifications of the product that is communicating.
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