
R8C/2C Group, R8C/2D Group
Rev.2.00
Dec 05, 2007
REJ09B0339-0200
14.3.9
Notes on Timer RC
14.3.9.1
TRC Register
The following note applies when the CCLR bit in the TRCCR1 register is set to 1 (clear TRC register at
compare match with TRCGRA register).
When using a program to write a value to the TRC register while the TSTART bit in the TRCMR register is
set to 1 (count starts), ensure that the write does not overlap with the timing with which the TRC register is
set to 0000h.
If the timing of the write to the TRC register and the setting of the TRC register to 0000h coincide, the
write value will not be written to the TRC register and the TRC register will be set to 0000h.
Reading from the TRC register immediately after writing to it can result in the value previous to the write
being read out. To prevent this, execute the JMP.B instruction between the read and the write instructions.
Program Example
MOV.W
#XXXXh, TRC
;Write
JMP.B
L1
;JMP.B instruction
L1:
MOV.W
TRC,DATA
;Read
14.3.9.2
TRCSR Register
Reading from the TRCSR register immediately after writing to it can result in the value previous to the write
being read out. To prevent this, execute the JMP.B instruction between the read and the write instructions.
Program Example
MOV.B
#XXh, TRCSR
;Write
JMP.B
L1
;JMP.B instruction
L1:
MOV.B
TRCSR,DATA
;Read
14.3.9.3
Count Source Switching
Stop the count before switching the count source.
Switching procedure
(1) Set the TSTART bit in the TRCMR register to 0 (count stops).
(2) Change the settings of bits TCK2 to TCK0 in the TRCCR1 register.
After switching the count source from fOCO40M to another clock, allow a minimum of two cycles of f1 to
elapse after changing the clock setting before stopping fOCO40M.
Switching procedure
(1) Set the TSTART bit in the TRCMR register to 0 (count stops).
(2) Change the settings of bits TCK2 to TCK0 in the TRCCR1 register.
(3) Wait for a minimum of two cycles of f1.
(4) Set the FRA00 bit in the FRA0 register to 0 (high-speed on-chip oscillator off).
14.3.9.4
Input Capture Function
The pulse width of the input capture signal should be three cycles or more of the timer RC operation clock
The value of the TRC register is transferred to the TRCGRj register one or two cycles of the timer RC
operation clock after the input capture signal is input to the TRCIOj (j = A, B, C, or D) pin (when the
digital filter function is not used).
14.3.9.5
TRCMR Register in PWM2 Mode
When the CSEL bit in the TRCCR2 register is set to 1 (count stops at compare match with the TRCGRA
register), do not set the TRCMR register at compare match timing of registers TRC and TRCGRA.