Preliminary User’s Manual U16846EJ1V0UD
82
CHAPTER 5 CLOCK GENERATOR
5.1 Functions of Clock Generator
The clock generator generates the clock to be supplied to the CPU and peripheral hardware.
The following two system clock oscillators are available.
•
High-speed system clock oscillator
The following two high-speed system clock oscillators are available.
•
Crystal/ceramic oscillator: Oscillates a clock of f
XP
= 2 to 16 MHz
•
External RC oscillator:
Oscillates a clock of f
XP
= 3 to 4 MHz
High-speed system clock oscillation can be selected using the option byte. Refer to CHAPTER 20 OPTION
BYTE for details.
The high-speed system clock oscillator can be stopped by executing the STOP instruction or setting the main
OSC control register (MOC).
•
Ring-OSC
oscillator
The Ring-OSC oscillator oscillates a clock of f
R
= 240 kHz (TYP.). Oscillation can be stopped by setting the
Ring-OSC mode register (RCM) when “Can be stopped by software” is set by the option byte and the high-
speed system clock is used as the CPU clock.
Remarks 1. f
XP
: High-speed system clock oscillation frequency
2.
f
R
: Ring-OSC clock oscillation frequency
5.2 Configuration of Clock Generator
The clock generator includes the following hardware.
Table 5-1. Configuration of Clock Generator
Item Configuration
Control registers
Processor clock control register (PCC)
Ring-OSC mode register (RCM)
Main clock mode register (MCM)
Main OSC control register (MOC)
Oscillation stabilization time counter status register (OSTC)
Oscillation stabilization time select register (OSTS)
System wait control register (VSWC)
Oscillator
High-speed system clock oscillator
Ring-OSC oscillator
