
Rev.2.10 Apr 14, 2006 page 56 of 378
REJ09B0124-0210
M16C/6N Group (M16C/6NK, M16C/6NM) 8. Clock Generation Circuit
8. Clock Generation Circuit
8.1 Types of Clock Generation Circuit
Four circuits are incorporated to generate the system clock signal:
• Main clock oscillation circuit
• Sub clock oscillation circuit
• On-chip oscillator
• PLL frequency synthesizer
Table 8.1 lists the Clock Generation Circuit Specifications. Figure 8.1 shows the Clock Generation Circuit.
Figures 8.2 to 8.8 show the clock-related registers.
Table 8.1 Clock Generation Circuit Specifications
Item
Main Clock
Oscillation Circuit
Sub Clock
Oscillation Circuit
On-chip Oscillator
PLL Frequency
Synthesizer
Use of clock
Clock
frequency
Usable
oscillator
Pins to connect
oscillator
Oscillation stop
and re-oscillation
detection function
Oscillation status
after reset
Other
• CPU clock source
• Peripheral function
clock source
0 to 16 MHz
•Ceramic oscillator
•Crystal oscillator
XIN, XOUT
Available
Oscillating
Externally derived clock can be input
• CPU clock source
• Clock source of timer
A, B
32.768 kHz
•Crystal oscillator
XCIN, XCOUT
Available
Stopped
• CPU clock source
• Peripheral function
clock source
• CPU and peripheral
function clock sources
when the main clock
stops oscillating
About 1 MHz
-
-
Available
Stopped
-
• CPU clock source
• Peripheral function
clock source
16 MHz, 20 MHz,
24 MHz
(1)
-
-
Available
Stopped
-
NOTE:
1. 24 MHz is available Normal-ver. only.
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