RL78/G13
Clock Generator (Clock Switching) CC-RL
R01AN2831EJ0100 Rev. 1.00
Page 26 of 51
May 28, 2015
Setting up clock generator operation mode
Clock operation mode control register (CMC)
: Select high-speed system clock pin operation mode.
Select subsystem clock pin operation mode.
Select XT1 oscillator oscillation mode.
Control X1 clock frequency.
Symbol: CMC
7 6 5 4 3
2 1
0
EXCLK
OSCSEL
EXCLKS
OSCSELS
0
AMPHS1
AMPHS0
AMPH
When HOCO clock is used
0 1 0 1
0
0
0 1
When X1 oscillation clock is used
When XT1 oscillation clock is used
Bits 7 and 6
EXCLK OSCSEL
High-speed system clock
pin operation mode
X1/P121 pin
X2/EXCLK/P122 pin
0
0
Input port mode
Input mode
0 1
X1 oscillation mode
Crystal/ceramic resonator connection
1
0
Input port mode
Input mode
1
1
External clock input mode Input mode
External clock input
Bits 5 and 4
EXCLKS OSCSELS
Subsystem clock
pin operation mode
XT1/P123 pin
XT2/EXCLKS/P124 pin
0
0
Input port mode
Input mode
0 1
XT1 oscillation mode
Crystal resonator connection
1
0
Input port mode
Input mode
1
1
External clock input mode Input mode
External clock input
Bits 2 and 1
AMPHS1 AMPHS0
XT1 oscillator oscillation mode selection
0 0
Low power consumption oscillation (default) Oscillation margin: Medium
0
1
Normal oscillation Oscillation margin: High
1 0
Ultra-low
power
consumption oscillation Oscillation margin: Low
1 1
Setting
prohibited
Bit 0
AMPHS
Control of X1 clock oscillation frequency
0 1
MHz
fx
10 MHz
1
10 MHz < fx
20 MHz
Caution: For details on the register setup procedures, refer to RL78/G13 User's Manual: Hardware.