
R8C/3GM Group
34. Usage Notes
R01UH0284EJ0100 Rev.1.00
Aug 09, 2011
After switching the count source from fOCO-F to fOCO40M, allow a minimum of two cycles of fOCO-F to
elapse after changing the clock setting before stopping fOCO-F.
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 fOCO-F.
(4) Set the FRA00 bit in the FRA0 register to 0 (high-speed on-chip oscillator off).
After switching the count source from fOCO-F to a clock other than fOCO40M, allow a minimum of one
cycle of fOCO-F + fOCO40M to elapse after changing the clock setting before stopping fOCO-F.
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 one cycle of fOCO-F + fOCO40M.
(4) Set the FRA00 bit in the FRA0 register to 0 (high-speed on-chip oscillator off).
34.8.5
Input Capture Function
Set the pulse width of the input capture signal as follows:
[When the digital filter is not used]
Three or more cycles of the timer RC operation clock (refer to Table 19.1 Timer RC Operation Clock)
[When the digital filter is used]
Five cycles of the digital filter sampling clock + three cycles of the timer RC operating clock, minimum (refer
to Figure 19.5 Digital Filter Block Diagram)
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).
When the input capture function is used, if an edge selected by bits IOj0 and IOj1 (j = A, B, C, or D) in the
TRCIOR0 or TRCIOR1 register is input to the TRCIOj pin, the IMFj bit in the TRCSR register is set to 1
even when the TSTART bit in the TRCMR register is 0 (count stops).
34.8.6
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.
34.8.7
Count Source fOCO40M
The count source fOCO40M can be used with supply voltage VCC = 2.7 to 5.5 V. For supply voltage other than
that, do not set bits TCK2 to TCK0 in the TRCCR1 register to 110b (select fOCO40M as the count source).