M32CSLASH8A datasheet(86/372 Pages) RENESAS

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M32C/8A Group

9. Clock Generation Circuits

Rev.1.00

Jul 15, 2007

Page 69 of 352

REJ09B0385-0100

Clock Generation Circuits

9.1

Types of the Clock Generation Circuit

The MCU has four on-chip clock generation circuits to generate system clock signals.

• Main clock oscillation circuit

• Sub clock oscillation circuit

• On-chip oscillator

• PLL frequency synthesizer

Table 9.1 lists the specifications of the clock generation circuit. Figure 9.1 shows a block diagram of the clock

generation circuit. Figures 9.2 to 9.8 show clock-associated registers.

Table 9.1

Clock Generation Circuit Specifications

Item

Main Clock Oscillation

Circuit

Sub Clock Oscillation

Circuit

On-chip Oscillator

PLL Frequency

Synthesizer

Applications

• CPU clock source

• Peripheral function

clock source

• CPU clock source

• Count source for

timer A and timer B

• CPU clock source

• Peripheral function

clock source

• CPU clock source

• Peripheral function

clock source

Clock frequency

Up to 32 MHz

32.768 kHz

Approx. 1 MHz

Up to 32 MHz

(see Table 9.3)

Connectable

oscillator or

resonator

• Ceramic resonator

• Crystal oscillator

Crystal oscillator

−−

Oscillator or

resonator

connect pins

XIN, XOUT

XCIN, XCOUT

−−

Oscillation stop/

restart function

Available

Oscillator state

after reset

Oscillating

Stopped

Other

Externally generated

clock can be used.

Externally generated

clock can be used.

Oscillation stop detect

function:

When the main clock

stops, the on-chip

oscillator starts

oscillating

automatically and

becomes the CPU

and peripheral

function clock source

30 MHz or 20 MHz:

Input 10 MHz to the

main clock

32 MHz or 21.3 MHz

Input 8 MHz to the

main clock

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