PD17225_15 Datasheet, PDF (31/86 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

µPD17225, 17226, 17227, 17228
4. CLOCK GENERATOR CIRCUIT
4.1 Instruction Execution Time (CPU Clock) Selection
The µPD17225 is equipped with a clock oscillator that supplies clocks to the CPU and hardware peripherals. Instruction
execution time can be changed in two steps (ordinary mode and high-speed mode) without changing the oscillation
frequency.
To change the instruction execution time, change the mode of SYSCK (RF: address 02H) of the register file by using
the POKE instruction.
Note, that the mode is actually only changed when the instruction next to the POKE instruction has been executed.
When using the high-speed mode, pay attention to the supply voltage. (Refer to 13. ELECTRICAL SPECIFICA-
TIONS.)
At reset, the ordinary mode is set.
3
2
0
0
1
0
Address: On reset: R/W:
0
SYSCK RF : 02H
0H
R/W
SYSCK
0
1
Selects Instruction Execution Time
Ordinary mode 32/fX (8µ s)
High-speed mode 16/fX (4µ s)
Figures in ( ): indicate figures when system clock fX = 4 MHz.
Data Sheet U12643EJ2V0DS00
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