Chapter 6 Clock Generator; Clock Generator Functions; Clock Generator Configuration - NEC mPD780973 Series Preliminary User's Manual

6.1 Clock Generator Functions

The clock generator generates the clock to be supplied to the CPU and peripheral hardware.
• Main system clock oscillator
This circuit oscillates at frequencies of 4.19 to 8.38 MHz. Oscillation can be stopped by executing the STOP
instruction or setting the processor clock control register (PCC).

6.2 Clock Generator Configuration

The clock generator consists of the following hardware.
X1
Main system
clock oscillator
X2
STOP
HALFOSC
Oscillator mode register

CHAPTER 6 CLOCK GENERATOR

Table 6-1. Clock Generator Configuration
Item
Control register Processor clock control register (PCC)
Oscillator mode register (OSCM)
Oscillator Main system clock oscillator
Note µ PD780973(A) only
Figure 6-1. Clock Generator Block Diagram
Prescaler
f
X
f f f f
X X X X
2 3 4
2 2 2 2
PCC2 PCC1
Internal bus
Configuration
Note
Prescaler
Standby
control
circuit
3
PCC0
Processor clock control register
Clock to
peripheral
hardware
CPU clock
(f )
CPU
89