S1C6S3N2 TECHNICAL SOFTWARE
EPSON
II-107
CHAPTER 7: SUMMARY OF NOTES
– Interrupt and HALT
(1) Even when the interrupt mask registers (ETI, EISWIT) are
set to "0", the interrupt factor flags (TI, SWIT) of the clock
timer and stopwatch counter can be set when the timing
conditions are established.
(2) When an interrupt is generated, three words of RAM are
used; also, it takes 12 cycles of the CPU system clock
until the value of the interrupt vector is set in the pro-
gram counter.
(3) When an interrupt occurs, the DI status (interrupt flag =
"0") comes into effect automatically.
(4) Reading of interrupt factor flags is available at EI, but be
careful in the following cases.
If the interrupt mask register value corresponding to the
interrupt factor flags to be read is set to "1", an interrupt
request will be generated by the interrupt factor flags set
timing, or an interrupt request will not be generated.
Be very careful when interrupt factor flags are in the
same address.
When the watchdog timer is used for the reset function, the
software must reset the watch dog timer within 3 seconds.
In this case, timer data (WD0–WD2) cannot be used for
timer applications.
(1) It takes at least 5 ms from the time the OSC3 oscillation
circuit goes ON until the oscillation stabilizes. Conse-
quently, when switching the CPU operation clock from
OSC1 to OSC3, do this after a minimum of 5 ms have
elapsed since the OSC3 oscillation went ON.
Further, the oscillation stabilization time varies depending
on the external oscillator characteristics and conditions of
use, so allow ample margin when setting the wait time.
(2) When switching the clock from OSC3 to OSC1, use a
separate instruction for switching the OSC3 oscillation
OFF.
(3) To lessen current consumption, keep OSC3 oscillation
OFF except when the CPU must be run at high speed.
Also, with S1C6S3N2/6S3L2/6S3B2, keep OSCC fixed to
"0".
– Watchdog Timer
– OSC3
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