HD64F3337YCP16V Datasheet, PDF (127/749 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 6 Clock Pulse Generator
6.1 Overview
The H8/3337 Series and H8/3397 Series have a built-in clock pulse generator (CPG) consisting of
an oscillator circuit, a duty adjustment circuit, and a divider and a prescaler that generates clock
signals for the on-chip supporting modules.
6.1.1 Block Diagram
Figure 6.1 shows a block diagram of the clock pulse generator.
XTAL
EXTAL
Oscillator
circuit
Duty
adjustment
circuit
ø
(system
clock)
ø_P
(for sup-
porting
modules)
Prescaler
Frequency
divider (1/2)
CKDBL
ø_P/2 to ø_P/4096
Figure 6.1 Block Diagram of Clock Pulse Generator
Input an external clock signal to the EXTAL pin, or connect a crystal resonator to the XTAL and
EXTAL pins. The system clock frequency (ø) will be the same as the input frequency. This same
system clock frequency (ø_P) can be supplied to timers and other supporting modules, or it can be
divided by two. The selection is made by software, by controlling the CKDBL bit.
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