UPD17217GT datasheet(28/84 Pages) NEC

Part #	UPD17217GT

Description	4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

PDF	84 Pages

Scroll/Zoom	100%

Manufacturer	NEC [NEC]

Direct Link	http://www.nec.com/

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28 / 84 page

µPD17215, 17216, 17217, 17218

CLOCK GENERATOR CIRCUIT

4.1

Instruction Execution Time (CPU Clock) Selection

The

µPD17215 is equipped with a clock oscillator circuit that supplies clocks to the CPU and hardware peri-pherals.

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 SPECIFICATIONS.)

At reset, the ordinary mode is set.

SYSCK

Address:

RF : 02H

SYSCK

On reset:

R/W:

R/W

Selects Instruction Execution Time

Ordinary mode 32/f (8 s)

High-speed mode 16/f (4 s)

Figures in ( ): indicate figures when system clock f = 4 MHz.

UPD17217GT Datasheet(PDF) 28 Page - NEC