R8C/1A Group, R8C/1B Group
20. Usage Notes
Rev.1.30
Dec 08, 2006
Page 304 of 315
REJ09B0252-0130
20.5.2
Notes on I
2
C bus Interface
Set the IICSEL bit in the PMR register to 1 (select I
2
C bus interface function) to use the I
2
C bus interface.
20.5.2.1
Accessing of Registers Associated with I
2
C bus Interface
Wait for three instructions or more or four cycles or more after writing to the same register among the registers
associated with the I
2
C bus Interface (00B8h to 00BFh) before reading it.
• An example of waiting three instructions or more
Program example
MOV.B
#00h,00BBh
; Set ICIER register to 00h
NOP
NOP
NOP
MOV.B
00BBh,R0L
• An example of waiting four cycles or more
Program example
BCLR
6,00BBh
; Disable transmit end interrupt request
JMP.B
NEXT
NEXT:
BSET
7,00BBh
; Enable transmit data empty interrupt request