Chapter 5 Clock Generator; Clock Generator Functions; Clock Generator Configuration - NEC mPD780852 Series Preliminary User's Manual

5.1 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 4.00 to 8.38 MHz. Oscillation can be stopped by executing the STOP
instruction.
Figure 5-1 shows clock generator block diagram.
X1 Main system
clock
X2
oscillator
STOP
HALFOSC
Oscillator mode register (OSCM)

5.2 Clock Generator Configuration

The clock generator consists of the following hardware.

CHAPTER 5 CLOCK GENERATOR

Figure 5-1. Clock Generator Block Diagram
Prescaler
f
X
f f f f
X X X X
2 3 4
2 2 2 2
Internal bus
Table 5-1. Clock Generator Configuration
Item
Control register Processor clock control register (PCC)
Oscillator mode register (OSCM)
Oscillator Main system clock oscillator
Note µ PD780851(A), 780852(A) only
Preliminary User's Manual U14581EJ3V0UM00
Prescaler
Standby
controller
3
PCC2 PCC1 PCC0
Processor clock control register (PCC)
Configuration
Note
Clock to
peripheral
hardware
CPU clock
(f )
CPU
91