UPD78F0138 NEC, UPD78F0138 Datasheet - Page 139

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

5.8 Clock Switching Flowchart and Register Setting
5.8.1 Switching from Ring-OSC clock to X1 input clock
Ring-OSC clock
Note Check the oscillation stabilization wait time of the X1 oscillator after reset release using the OSTC register
Register value
X1 input clock
operation
after reset
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.
Figure 5-14. Switching from Ring-OSC Clock to X1 Input Clock (Flowchart)
X1 oscillation stabilization
(dividing set PCC)
clock operation
time has not elapsed
Ring-OSC
CHAPTER 5 CLOCK GENERATOR
X1 input clock operation
User’s Manual U16228EJ2V0UD
Each processing
OSTS = 05H
OSTC check
OSTC = 00H
RCM = 00H
MCM = 00H
MOC = 00H
PCC setting
MCM.0
PCC = 00H
After reset
X1 oscillation stabilization time has elapsed
1
Note
Note
; f
; Ring-OSC oscillation
; Ring-OSC clock operation
; X1 oscillation
; Oscillation stabilization time status register
; Oscillation stabilization time f
CPU
; X1 oscillation stabilization time status check
MCM.1 (MCS) is changed from 0 to 1
= f
R
XP
/2
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