Hi Bill,

You got the WDT right.

I must say that i've gone through more than my share of Microchips datasheets and i can't remember ever seeing anything else than the usual 0,2-0,8Vdd spec for ST inputs. So if you're running your pic on 5v, anything less than 1v(0,2*Vdd) is guaranteed to be read as a 0(low) by the pic. Anything above 4v(0,8*Vdd) is guaranteed to be seen as 1(high). Everything in between is to be considered as unknown. This means that your trippoint should be found somewhere in this region. It does not say anything about the amount of hysteresis. I haven't checked this for many years but when i did i found that the trippoint was just below 0.5Vdd and the hysteresis was quite small (<100mv). My memory may be way off though.

So, if i need an input with a specified trippoint and a specified ammount of hysteresis i use a comparator(or op) with external resistors.

/Ingvar