Clock Generator Control Register - NEC PD789860 User Manual

8.3 Clock Generator Control Register

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 the division ratio.
PCC is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets PCC to 02H.
Symbol 7 6
PCC 0 0
PCC0
0 f
CC
2
f /2
1
CC
Caution Be sure to clear bits 0 and 2 to 7 to 0.
Remark f : System clock oscillation frequency
CC
CHAPTER 8 CLOCK GENERATOR (
Figure 8-2. Format of Processor Clock Control Register
5 4 3
0 0 0
CPU clock (f ) selection
CPU
User's Manual U14826EJ5V0UD
µ
PD789861 SUBSERIES)
2 1 0 Address
0 PCC0 0
Minimum instruction execution time: 2/f
At f = 1.0 MHz operation
CC
µ
2.0 s
µ
8.0 s
After reset R/W
FFFBH 02H R/W
CPU
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