Programming Notes - Epson S1C6S3N2 Technical Manual

(2) Switching from OSC3 to OSC1
Specifications
Program
Note

Programming notes

S1C6S3N2 TECHNICAL SOFTWARE
This subroutine switches the CPU clock to OSC1, and then
sets OSC3 to OFF.
OS1: LD
AND
;
AND
RET
To prevent an error, first switch OSC1, and then set OSC3
to OFF in the next step.
(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 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.
(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".
EPSON
CHAPTER 5: PERIPHERAL CIRCUITS (OSC3)
X,0FEH ; Switche the CPU clock to OSC1
MX,1011B ;
MX,1101B ;
Set OSC3 to OFF
; Return to parent routine
II-27