Datasheet

Section 14 Timer RB
Page 432 of 982 REJ09B0465-0300 Rev. 3.00
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
14.3.3 Programmable One-Shot Generation Mode
This mode outputs one-shot pulses from the TRBO pin, based on either program or external
trigger input. When a trigger is generated, beginning with that point in time the timer operates
only once for any length of time specified in TRBPR. TRBSC is not used in this mode. In this
mode, TRBPRE or TRBPR should not be set to H'00.
(1) Starting and Stopping Operation
The counting is started when 1 is written to the TOSST bit in TRBOCR or a valid trigger signal is
input to the TRGB pin after the TSTART bit in TRBCR is set to 1 and the TCSTF flag is set to 1.
For a trigger input, the pulse must be longer than one cycle of the clock source for counting.
The counting is stopped when reloading is performed with an underflow of the counter, when 1 is
written to the TOSSP bit in TRBOCR, or when 0 is written to the TSTART bit in TRBCR.
(2) Forced Termination of Operation
Writing 1 to the TSTOP bit in TRBCR stops the counting forcedly. When the counting is forcedly
stopped, the timer RB counter, the prescaler counter, and any associated flags are initialized.
(3) Interrupt Request
An interrupt request is generated on the underflow of the timer RB counter.
(4) Reading and Writing Count Value
Reading TRBPRE and TRBTR reads count values from each register.
If a write is performed to TRBPRE or TRBPR when counting is stopped, set values are written to
both the reload register and the counter.
If a write is performed to TRBPRE or TRBPR during counting, data is written only to the
respective reload registers. The value written to TRBPRE takes effect in synchronization with the
underflow of the prescaler. The value written to TRBPR takes effect during the next one-shot
pulse.
Figure 14.3 shows an operation example of the timer RB in programmable one-shot generation
mode.