
CHAPTER 5 CLOCK GENERATOR
84
Figure 5-3. Processor Clock Control Register Format
PCC0
PCC
7
6
5
4
3
2
Symbol
1
0
CSS
CPU Clock (f
CPU
) selection
Note 2
FFFBH
PCC1
0
PCC2
CSS
CLS
FRC
MCC
Address
After Reset
R/W
04H
R/W
Note 1
f
X
f
X
/2
f
X
/2
2
f
X
/2
3
f
X
/2
4
f
XT
/2
Other than above
Setting prohibited
CLS
CPU Clock Status
0
Main system clock
1
Subsystem clock
FRC
Subsystem Clock Feedback Resistor Selection
0
Internal feedback resistor used
1
Internal feedback resistor not used
MCC
Main System Clock Oscillation Control
Note 3
0
Oscillation possible
1
Oscillation stopped
PCC2
0
0
0
0
1
0
0
1
0
1
PCC1
0
0
1
1
0
0
0
1
1
0
PCC0
0
1
0
1
0
0
1
0
1
0
0
0
R/W
R
R/W
R/W
Notes 1.
Bit 5 is Read Only.
2.
FIP can be displayed only when CSS is 0 and PCC2 to PCC0 are 000 or 001.
3.
When the CPU is operating on the subsystem clock, MCC should be used to stop the main system
clock oscillation. A STOP instruction should not be used.
Caution
Bit 3 must be set to 0.
Remarks 1.
f
X
: Main system clock oscillation frequency
2.
f
XT
: Subsystem clock oscillation frequency