UPD17708 datasheet(322/356 Pages) NEC

322 / 356 page

322

µPD17704, 17705, 17707, 17708, 17709

21.6.2 Watchdog timer setting flags

These flags can be set only once after power-ON reset on power application or reset by the RESET pin.

The WDTCK0 and WDTCK1 flags select an interval at which the reset signal is output.

The reference time can be selected to the following three conditions:

•

655356 instructions

•

131072 instructions

•

Watchdog timer not set

On power application, 131072 instructions are selected.

If the reset signal generation interval is specified to be 131072 instructions, the watchdog timer FF must be reset

at intervals not exceeding 131072 instructions. The valid reset period is from 1 to 131071 instructions.

If the reset signal generation interval is 65536 instructions, the watchdog timer FF must be reset at intervals not

exceeding 65536 instrutions. The valid reset period is from 1 to 65535 instructions.

Figure 21-12. Configuration of Watchdog Timer Clock Selection Register

Name

Flag symbol

Address

02H

Read/Write

R/WNote

Watchdog timer

clock selection

Power-ON reset

WDT&SP reset

CE reset

Clock stop

011

Does not set watchdog timer

65536 instructions

Setting prohibited

131072 instructions

Selects clock of watchdog timer

Fixed to “0”

Retained

Note

Can be written only once.

UPD17708 데이터시트(PDF) 322 Page - NEC