upd78f0103hmca1-5a4-a Renesas Electronics Corporation., upd78f0103hmca1-5a4-a Datasheet - Page 100

• Manufacturer Part Number: upd78f0103hmca1-5a4-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

5.8 Clock Switching Flowchart and Register Setting
5.8.1 Switching from internal oscillation clock to high-speed system clock
100
Note Check the oscillation stabilization wait time of the high-speed system clock oscillator after reset release
Internal oscillation
High-speed system
clock operation
value after reset
clock operation
Register initial
Figure 5-14. Switching from Internal Oscillation Clock to High-Speed System Clock (Flowchart)
using the OSTC register and then switch to the high-speed system clock operation after the oscillation
stabilization wait time has elapsed. Waiting for the oscillation stabilization time is not required when the
external RC oscillation clock is selected as the high-speed system clock by the option byte. Therefore, the
CPU clock can be switched without reading the OSTC value. The OSTS register setting is valid only after
STOP mode is released by interrupt during high-speed system clock operation.
clock oscillation stabilization
Internal oscillation
(dividing set PCC)
clock operation
time has not elapsed
High-speed system
CHAPTER 5 CLOCK GENERATOR
High-speed system clock operation
User’s Manual U16846EJ3V0UD
After reset release
Each processing
OSTS = 05H
OSTC check
OSTC = 00H
MCM = 00H
MOC = 00H
PCC setting
MCM.0 ← 1
RCM = 00H
PCC = 00H
High-speed system clock oscillation stabilization time
has elapsed
Note
Note
; f
; Internal oscillation
; Internal oscillation clock operation
; High-speed system clock oscillation
; Oscillation stabilization time status register
; Oscillation stabilization time f
CPU
; High-speed system clock oscillation
stabilization time status check
MCM.1 (MCS) is changed from 0 to 1
= f
R
XP
/2
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