R8C/20 Group, R8C/21 Group 14. Timers
Rev.2.00 Aug 27, 2008 Page 158 of 458
REJ09B0250-0200
14.2.5.4 Programmable wait one-shot generation mode
The following three workarounds should be performed in programmable wait one-shot generation mode.
(1) To write to registers TRBPRE and TRBPR during count operation (TCSTF bit is set to 1), note the
following points:
• When the TRBPRE register is written continuously, allow three or more cycles of the count source for each
write interval.
• When the TRBPR register is written continuously, allow three or more cycles of the prescaler underflow
for each write interval.
(2) Do not set both the TRBPRE and TRBPR registers to 00h.
(3) Set registers TRBSC and TRBPR using the following procedure.
(a) To use “INT0
pin one-shot trigger enabled” as the count start condition
Set the TRBSC register and then the TRBPR register. At this time, after writing to the TRBPR
register, allow an interval of 0.5 or more cycles of the count source before trigger input from the
INT0
pin.
(b) To use “writing 1 to TOSST bit” as the start condition
Set the TRBSC register, the TRBPR register, and then TOSST bit. At this time, after writing to the
TRBPR register, allow an interval of 0.5 or more cycles of the count source before writing to the
TOSST bit.