Programming Notes - Epson 0C88832 Technical Manual

5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Oscillation Circuits and Operating Mode)

5.3.8 Programming notes

(1) When the high speed CPU operation is not
necessary, you should operate the peripheral
circuits according to the setting outline indicate
below.
• CPU operating clock
OSC1
• OSC3 oscillation circuit
OFF (When the OSC3 clock is not necessary
for some peripheral circuits.)
• Operating mode
Low power mode (When V
or less)
or Normal mode (When V
more)
(2) Do not turn the OSC3 oscillation circuit ON in
the low power mode.
Do not switch over the operating mode (normal
mode ↔ high speed mode) in the OSC3 oscilla-
tion circuit ON status, as this will cause faulty
operation.
(3) When turning ON the OSC3 oscillation circuit
after switching the operating mode, you should
allow a minimum waiting time of 5 msec.
(4) Since several 100 µsec to several 10 msec are
necessary for the oscillation to stabilize after
turning the OSC3 oscillation circuit ON.
Consequently, you should switch the CPU
operating clock (OSC1 → OSC3) after allowing
for a sufficient waiting time once the OSC3
oscillation goes ON. (The oscillation start time
will vary somewhat depending on the oscillator
and on the externally attached parts. Refer to
the oscillation start time example indicated in
Chapter 7, "ELECTRICAL CHARACTERIS-
TICS".)
(5) When switching the clock from OSC3 to OSC1,
be sure to switch OSC3 oscillation OFF with
separate instructions. Using a single instruction
to process simultaneously can cause a malfunc-
tion of the CPU.
32
–V is 3.5 V
DD SS
–V is 3.5 V or
DD SS
EPSON
E0C88832/88862 TECHNICAL MANUAL