M32C8A Datasheet, PDF (86/372 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M32C/80 Series

M32C/8A Group
9. Clock Generation Circuits
9. 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 Sub Clock Oscillation
Circuit
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
• Ceramic resonator Crystal oscillator
−
−
oscillator or
• Crystal oscillator
resonator
Oscillator or
XIN, XOUT
XCIN, XCOUT
−
−
resonator
connect pins
Oscillation stop/ Available
restart function
Available
Available
Available
Oscillator state Oscillating
after reset
Stopped
Stopped
Stopped
Other
Externally generated
clock can be used.
Externally generated
clock can be used.
Oscillation stop detect 30 MHz or 20 MHz:
function:
Input 10 MHz to the
When the main clock main clock
stops, the on-chip 32 MHz or 21.3 MHz
oscillator starts
Input 8 MHz to the
oscillating
main clock
automatically and
becomes the CPU
and peripheral
function clock source
Rev.1.00 Jul 15, 2007 Page 69 of 352
REJ09B0385-0100