Setup WDT for a PIC18

Alejandro · Joined: 25 Mar 2011 Posts: 7

Hi, I have several doubt about how working with WDT on a PIC18, I am work with pic18f452 at 20MHz

which means WDT128?
How I have to do to set a timeout of WDT of 30sec ?

someone can clarify this doubt !!!

collink · Joined: 08 Jan 2010 Posts: 137 Location: Michigan

Normally I'd say look at the manual but the manual is a mess in this regard. At least for your chip. It's better for some of the other pic chips. Anyway, your manual says that the watchdog timer will be at least 7ms, probably 18, and at most 33ms at WDT1. Every value higher than one multiplies this. So WDT2 would be 18 * 2 = 36ms. WDT128 is 128 * 18ms = 2304ms. So I don't see any way that you can set a WDT timeout of 30seconds with your pic chip.