5.8 Clock Switching Flowchart and Register Setting
5.8.1 Switching from Ring-OSC clock to X1 input clock
Figure 5-14. Switching from Ring-OSC Clock to X1 Input Clock (Flowchart)
Register initial
value after reset
X1 oscillation stabilization
Ring-OSC clock
time has not elapsed
operation
Ring-OSC
clock operation
(dividing set PCC)
X1 input clock
operation
Note Check the oscillation stabilization wait time of the X1 oscillator after reset release using the OSTC register
and then switch to the X1 input clock operation after the oscillation stabilization wait time has elapsed. The
OSTS register setting is valid only after STOP mode is released by interrupt during X1 input clock operation.
CHAPTER 5 CLOCK GENERATOR
After reset release
PCC = 00H
RCM = 00H
MCM = 00H
MOC = 00H
OSTC = 00H
Note
OSTS = 05H
Each processing
Note
OSTC check
X1 oscillation stabilization time has elapsed
PCC setting
MCM.0 ← 1
X1 input clock operation
User's Manual U16227EJ2V0UD
; f
= f
CPU
R
; Ring-OSC oscillation
; Ring-OSC clock operation
; X1 oscillation
; Oscillation stabilization time status register
; Oscillation stabilization time f
; X1 oscillation stabilization time status check
MCM.1 (MCS) is changed from 0 to 1
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/2
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