Specifications

Table Of Contents
II-16 EPSON S1C62740 TECHNICAL SOFTWARE
CHAPTER 6: PERIPHERAL CIRCUITS (OSC3)
OR MX,CLKCHG ;CHANGE CLOCK TO OSC3
RET
;
OS1:
;* CHANGE CLOCK FRWQUENCY FROM OSC3 TO OSC1
LD X,ZOSCC ;CHANGE CLOCK TO OSC1
AND MX,(NOT CLKCHG) AND 0FH
;CHANGE CLOCK TO OSC1
;
AND MX,(NOT OSCC) AND 0FH
;SET OSC3 TO OFF
RET
;
(1) It takes at least 5 msec from the time the OSC3 oscillation
circuit goes ON until the oscillation stabilizes. Consequently,
when switching the CPU operation clock from OSC1 to OSC3,
do this after a minimum of 5 msec 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. An error in
the CPU operation can result if this processing is performed at
the same time by the one instruction.
(3) To lessen current consumption, keep OSC3 oscillation OFF
except when the CPU must be run at high speed.
(4) When shifting to the SLEEP status, the CPU clock must be set
to OSC1 and the OSC3 oscillation circuit must be OFF.
Programming notes