UPD17217CT-XXX View Datasheet(PDF) - NEC => Renesas Technology

Part Name

Description

Manufacturer

UPD17217CT-XXX

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

NEC => Renesas Technology 

µPD17215, 17216, 17217, 17218

4. 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.

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/f X (8 µs)

High-speed mode 16/f X (4 µs)

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

28

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