RL78/G15 CHAPTER 13 SERIAL INTERFACE IICA
R01UH0959EJ0110 Rev.1.10 Page 521 of 765
Mar 7, 2023
13.3.4 IICA flag register 0 (IICF0)
This register sets the operation mode of I
2
C and indicates the state of the I
2
C bus.
The IICF0 register can be set by a 1-bit or 8-bit memory manipulation instruction. However, the STT0 clear flag (STCF0)
and I
2
C bus status flag (IICBSY0) bits are read-only.
The IICRSV0 bit can be used to enable or disable communication reservation.
The STCEN0 bit can be used to set the initial value of the IICBSY0 bit.
The IICRSV0 and STCEN0 bits can only be written while operation of I
2
C is disabled (bit 7 (IICE0) of IICA control register
00 (IICCTL00) = 0). The IICF0 register is only readable after the operation is enabled.
Reset signal generation clears this register to 00H.
Figure 13-8. Format of IICA Flag Register 0 (IICF0) (1/2)
Address: FFF52H After reset: 00H R/W
Note 1
Symbol
□
7
□
6 5 4 3 2
□
1
□
0
IICF0 STCF0 IICBSY0 0 0 0 0 STCEN0 IICRSV0
STCF0 STT0 clear flag
0 A start condition is generated.
1 A start condition cannot be generated and the STT0 flag is cleared.
Condition for clearing (STCF0 = 0) Condition for setting (STCF0 = 1)
●
Cleared by STT0 = 1
●
When IICE0 = 0 (operation stop)
●
Reset
●
A start condition cannot be generated when
communication reservation is disabled (IICRSV0 = 1)
and the STT0 bit is cleared to 0.
IICBSY0 I
2
C bus status flag
0 Bus released state (the initial state of communication when STCEN0 = 1)
1 Bus communication state (the initial state of communication when STCEN0 = 0)
Condition for clearing (IICBSY0 = 0) Condition for setting (IICBSY0 = 1)
●
When a stop condition is detected
●
When IICE0 = 0 (operation stop)
●
Reset
●
When a start condition is detected
●
Setting of the IICE0 bit when STCEN0 = 0
STCEN0 Initial start enable trigger
0
After operation is enabled (IICE0 = 1), enable generation of a start condition upon detection of a stop
condition.
1
After operation is enabled (IICE0 = 1), enable generation of a start condition without detecting a stop
condition.
Condition for clearing (STCEN0 = 0) Condition for setting (STCEN0 = 1)
●
Cleared by instruction
●
When a start condition is detected
●
Reset
●
Set by instruction
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