10. Clock Generation Circuit - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group

10. Clock Generation Circuit

The clock generation circuit has:
• Main clock oscillation circuit
• On-chip oscillator (oscillation stop detection function)
Table 10.1 lists Specifications of Clock Generation Circuit. Figure 10.1 shows a Clock Generation Circuit.
Figures 9.2 to 10.5 show clock associated registers.
Table 10.1 Specifications of Clock Generation Circuit
Item
Applications
Clock frequency
Connectable
oscillator
Oscillator
connect pins
Oscillation stop,
restart function
Oscillator status
after reset
Others
NOTE:
1. These pins can be used as P4_6 or P4_7 when using the on-chip oscillator clock as the CPU clock
while the main clock oscillation circuit is not used.
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
Main Clock
Oscillation Circuit
High-Speed On-Chip Oscillator
• CPU clock source • CPU clock source
• Peripheral • Peripheral function clock
function clock source
source • CPU and peripheral function
clock sources when main
clock stops oscillating
0 to 20 MHz Approx. 8 MHz
−
• Ceramic
resonator
• Crystal oscillator
(Note 1)
(1)
XIN, XOUT
Usable Usable
Stop Stop
−
Externally
generated clock
can be input
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10. Clock Generation Circuit
On-Chip Oscillator
Low-Speed On-Chip Oscillator
• CPU clock source
• Peripheral function clock
source
• CPU and peripheral function
clock sources when main
clock stops oscillating
Approx. 125 kHz
−
(Note 1)
Usable
Oscillate
−