HT82K68 datasheet(19/40 Pages) HOLTEK

19 / 40 page

No.

ROM Code Option

OSC type selection. This option is to decide if an RC or Crystal oscillator is chosen as system

clock. If the Crystal oscillator is selected, the XST (Crystal Start-up Timer) default is acti-

vated, otherwise the XST is disabled.

WDT source selection. There are three types of selection: on-chip RC oscillator, instruction

clock or disable the WDT.

CLRWDT times selection. This option defines the way to clear the WDT by instruction. ²One

time² means that the CLR WDT instruction can clear the WDT. ²Two times² means only if

both of the CLR WDT1 and CLR WDT2 instructions have been executed, only then will the

WDT be cleared.

Wake-up selection. This option defines the wake-up function activity. External I/O pins (PA

and PC [0:3] only) all have the capability to wake-up the chip from a HALT.

Pull-high selection. This option is to decide whether the pull-high resistance is visible or not

in the input mode of the I/O ports. Each bit of an I/O port can be independently selected.

Special power on reset. This option defines the function will reset the chip to prevent incor-

rect status.

If the special power on reset is enabled, the chip must not enter the HALT mode.

HT82K68E

August 8, 2000

Preliminary

ROM code option

The following shows six kinds of ROM code option in the HT82K68E. All the ROM code options must

be defined to ensure proper system function.

HT82K68 Datasheet(PDF) 19 Page - Holtek Semiconductor Inc