M32C80 Datasheet, PDF (75/352 Pages) Renesas Technology Corp – 16/32-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M32C/80 SERIES

M32C/80 Group
8. Clock Generation Circuit
8. Clock Generation Circuit
8.1 Types of the Clock Generation Circuit
Four circuits are included to generate the system clock signal:
• Main clock oscillation circuit
• Sub clock oscillation circuit
• On-chip oscillator
• PLL frequency synthesizer
Table 8.1 lists specifications of the clock generation circuit. Figure 8.1 shows a block diagram of the clock
generation circuit. Figures 8.2 to 8.8 show registers controlling the clock.
Table 8.1 Clock Generation Circuit Specifications
Item
Main Clock
Oscillation Circuit
Sub Clock
Oscillation Circuit
Use
CPU clock source,
CPU clock source,
Peripheral function
Timer A and B clock
clock source
source
Clock Frequency Up to 32 MHz
32.768 kHz
Connectable
Osillator or
Additional Circuit
Pins for Oscillator
or for Additional
Circuit
Oscillation Stop /
Restart Function
Oscillator State
after Reset
Other
Ceramic resonator
Crystal oscillator
XIN, XOUT
Available
Oscillating
Externally generated
clock can be applied.
Crystal oscillator
XCIN, XCOUT
Available
Stopped
Externally generated
clock can be applied.
On-chip Oscillator
CPU clock source,
Peripheral function
clock source
Approx. 1 MHz
PLL Frequency
Synthesizer
CPU clock source,
Peripheral function
clock source
Up to 32 MHz
(See Table 8.3)
---
---
---
---
Available
Available
Stopped
Stopped
When the main clock ---
stops oscillating, the
on-chip oscillator
starts oscillating auto-
matically and
becomes clock source
for the CPU and
peripheral function.
Rev. 1.00 Nov. 01, 2005 Page 56 of 330
REJ09B0271-0100