Chapter 5 Clock Generator; Clock Generator Functions; Clock Generator Configuration; Configuration Of Clock Generator - NEC PD789488 User Manual

5.1 Clock Generator Functions

The clock generator generates the clock to be supplied to the CPU and peripheral hardware.
The following two types of system clock oscillators are used.
• Main system clock oscillator
This circuit oscillates at 1.0 to 5.0 MHz. Oscillation can be stopped by executing the STOP instruction or setting
the processor clock control register (PCC).
• Subsystem clock oscillator
This circuit oscillates at 32.768 kHz. Oscillation can be stopped by the suboscillation mode register (SCKM).
Also, a circuit to multiply the subsystem clock by 4 can be used by setting a mask option or the subclock
selection register (SSCK).

5.2 Clock Generator Configuration

The clock generator includes the following hardware.
Item
Control registers
Oscillators

CHAPTER 5 CLOCK GENERATOR

Table 5-1. Configuration of Clock Generator
Processor clock control register (PCC)
Subclock oscillation mode register (SCKM)
Subclock control register (CSS)
Subclock selection register (SSCK) (
Main system clock oscillator
Subsystem clock oscillator
User's Manual U15331EJ4V1UD
Configuration
µ
PD78F9488, 78F9489 only)
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