UPD78F0411GA-GAM-AX Datasheet, PDF (141/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 5 CLOCK GENERATOR
5.6.7 Condition before changing CPU clock and processing after changing CPU clock
Condition before changing the CPU clock and processing after changing the CPU clock are shown below.
Table 5-6. Changing CPU Clock
CPU Clock
Before Change After Change
Internal high-
speed oscillation
clock
X1 clock
External main
system clock
X1 clock
External main
system clock
Internal high-
speed oscillation
clock
X1 clock
External main
system clock
XT1 clock
Internal high-
speed oscillation
clock
XT1 clock
Internal high-
speed oscillation
clock
X1 clock
External main
system clock
Condition Before Change
Processing After Change
Stabilization of X1 oscillation
• MSTOP = 0, OSCSEL = 1, EXCLK = 0
• After elapse of oscillation stabilization time
• Internal high-speed oscillator can be
stopped (RSTOP = 1).
Enabling input of external clock from EXCLK
pin
• MSTOP = 0, OSCSEL = 1, EXCLK = 1
Oscillation of internal high-speed oscillator
• RSTOP = 0
X1 oscillation can be stopped (MSTOP = 1).
External main system clock input can be
disabled (MSTOP = 1).
Stabilization of XT1 oscillation
• OSCSELS = 1
• After elapse of oscillation stabilization time
Operating current can be reduced by
stopping internal high-speed oscillator
(RSTOP = 1).
X1 oscillation can be stopped (MSTOP = 1).
External main system clock input can be
disabled (MSTOP = 1).
Oscillation of internal high-speed oscillator
and selection of internal high-speed
oscillation clock as main system clock
• RSTOP = 0, MCS = 0
XT1 oscillation can be stopped (OSCSELS
= 0).
Stabilization of X1 oscillation and selection
of high-speed system clock as main system
clock
• MSTOP = 0, OSCSEL = 1, EXCLK = 0
• After elapse of oscillation stabilization time
• MCS = 1
Enabling input of external clock from EXCLK
pin and selection of high-speed system
clock as main system clock
• MSTOP = 0, OSCSEL = 1, EXCLK = 1
• MCS = 1
User’s Manual U18698EJ1V0UD
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