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5.3 Register Controlling Clock Generator
The clock generator is controlled by the following register.
• Processor clock control register (PCC)
(1) Processor clock control register (PCC)
PCC selects the CPU clock and sets the of division ratio.
PCC is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets the PCC to 02H.
Symbol
7
6
5
PCC
0
0
0
PCC1
0
f
X
1
f
/2
2
X
Caution
Bits 0 and 2 to 7 must be set to 0.
Remark f
: system clock oscillation frequency
X
74
CHAPTER 5
CLOCK GENERATOR
Figure 5-2. Format of Processor Clock Control Register
4
3
2
1
0
0
0
PCC1
CPU clock (f
) selection
CPU
User's Manual U12978EJ3V0UD
0
Address
After reset
0
FFFBH
02H
Minimum instruction execution time: 2/f
f
X
µ
0.33 s
µ
1.33 s
R/W
R/W
CPU
= 6.0 MHz operation
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