CHAPTER 5 CLOCK GENERATOR
User’s Manual U12978EJ3V0UD
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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.
Figure 5-2. Format of Processor Clock Control Register
CPU clock (fCPU) selection
000000PCC1 0PCC
Symbol Address After reset R/W
FFFBH 02H R/W
76543210
PCC1
0
1
fX
fX/22
µ
µ
Minimum instruction execution time: 2/fCPU
0.33 s
1.33 s
fX = 6.0 MHz operation
Caution Bits 0 and 2 to 7 must be set to 0.
Remark fX: system clock oscillation frequency