Registers Controlling Clock Generator - NEC 78K0 Series User Manual

Remarks 1. f : X1 clock oscillation frequency
X
2. f : Internal high-speed oscillation clock frequency
RH
3. f : External main system clock frequency
EXCLK
4. f : High-speed system clock oscillation frequency
XH
5. f : Main system clock oscillation frequency
XP
6. f : Peripheral hardware clock oscillation frequency
PRS
7. f : CPU clock oscillation frequency
CPU
8. f : XT1 clock oscillation frequency
XT
9. f : External subsystem clock frequency
EXCLKS
10. f : Subsystem clock oscillation frequency
SUB
11. f : Internal low-speed oscillation clock frequency
RL

6.3 Registers Controlling Clock Generator

The following seven registers are used to control the clock generator.
• Clock operation mode select register (OSCCTL)
• Processor clock control register (PCC)
• Internal oscillation mode register (RCM)
• Main OSC control register (MOC)
• Main clock mode register (MCM)
• Oscillation stabilization time counter status register (OSTC)
• Oscillation stabilization time select register (OSTS)
(1) Clock operation mode select register (OSCCTL)
This register selects the operation modes of the high-speed system and subsystem clocks, and the gain of the
on-chip oscillator.
OSCCTL can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets this register to 00H.
CHAPTER 6 CLOCK GENERATOR
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