UPD78F0411GA-GAM-AX Datasheet, PDF (108/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

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 three kinds of system clocks and clock oscillators are selectable.
(1) Main system clock
<1> X1 oscillator
This circuit oscillates a clock of fX = 2 to 10 MHz by connecting a resonator to X1 and X2.
Oscillation can be stopped by executing the STOP instruction or using the main OSC control register
(MOC).
<2> Internal high-speed oscillator
This circuit oscillates a clock of fRH = 8 MHz (TYP.). After a reset release, the CPU always starts
operating with this internal high-speed oscillation clock. Oscillation can be stopped by executing the
STOP instruction or using the internal oscillation mode register (RCM).
An external main system clock (fEXCLK = 2 to 10 MHz) can also be supplied from the OCD0B/EXCLK/X2/P122
pin. An external main system clock input can be disabled by executing the STOP instruction or using RCM.
As the main system clock, a high-speed system clock (X1 clock or external main system clock) or internal high-
speed oscillation clock can be selected by using the main clock mode register (MCM).
(2) Subsystem clock
• Subsystem clock oscillator
This circuit oscillates at a frequency of fXT = 32.768 kHz by connecting a 32.768 kHz resonator across XT1
and XT2. Oscillation can be stopped by using the processor clock control register (PCC) and clock
operation mode select register (OSCCTL).
Remarks 1. fX:
2. fRH:
3. fEXCLK:
4. fXT:
X1 clock oscillation frequency
Internal high-speed oscillation clock frequency
External main system clock frequency
XT1 clock oscillation frequency
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User’s Manual U18698EJ1V0UD