I-98
EPSON
S1C6S3N2 TECHNICAL HARDWARE
CHAPTER 5: SUMMARY OF NOTES
Summary of Notes by Function
Here, the cautionary notes are summed up by function
category. Keep these notes well in mind when programming.
Memory is not mounted in unused area within the memory
map and in memory area not indicated in this manual. For this
reason, normal operation cannot be assured for programs that
have been prepared with access to these areas.
When the watchdog timer is being used, the software must
reset it within 3-second cycles, and timer data (WD0–WD2)
cannot be used for timer applications.
(1) It takes at least 5 ms from the time the OSC3 oscillation
circuit starts operating until the oscillation stabilizes.
Consequently, 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 depend-
ing on the external oscillator characteristics and condi-
tions 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. An error in the CPU operation can result if this
processing is performed at the same time by the one
instruction.
(1) When input ports are changed from high to low by pull-
down resistance, the fall of the waveform is delayed on
account of the time constant of the pull-down resistance
and input gate capacitance. Hence, when fetching input
ports, set an appropriate wait time. Particular care needs
to be taken of the key scan during key matrix configura-
tion. Aim for a wait time of about 1 ms.
5.2
Memory
Watchdog timer
Oscillation circuit
and prescaler
Input port
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