Programming Notes - Epson 0C88832 Technical Manual

5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Stopwatch Timer)

5.9.5 Programming notes

(1) The stopwatch timer is actually made to RUN/
STOP in synchronization with the falling edge
of the 256 Hz signal after writing to the SWRUN
register. Consequently, when "0" is written to
the SWRUN, the timer shifts to STOP status
when the counter is incremented "1". The
SWRUN maintains "1" for reading until the
timer actually shifts to STOP status.
Figure 5.9.5.1 shows the timing chart of the
RUN/STOP control.
256 Hz
SWRUN(RD)
SWRUN(WR)
SWDX 27 28
Fig. 5.9.5.1 Timing chart of RUN/STOP control
(2) The SLP instruction is executed when the
stopwatch timer is in the RUN status (SWRUN
= "1"). The stopwatch timer operation will
become unstable when returning from SLEEP
status. Therefore, when shifting to SLEEP
status, set the clock timer to STOP status
(SWRUN = "0") prior to executing the SLP
instruction.
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E0C88832/88862 TECHNICAL MANUAL