i had a similar problem in a PIC18F458 ICSP circuit. then i realised i
didn't take it 5V for LVP .
in normal operation VIHH is btw 2.5V and 5.5 V but for LVP it must be btw
4.5V  and 5V.
and may be u should set LVP bit enable from config. bits.

-----Original Message-----
From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On
Behalf Of Wouter van Ooijen
Sent: Monday, January 05, 2004 1:52 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] VIHH on MCLR doesnt put PIC in programming mode


> After doing more testing on my ICSP circuit I strongly
> believe that the
> PIC isn't going into programming mode once VIHH is applied to MCLR. It
> simply goes along and executes code as normal. Has anyone seen similar
> behaviour?

Is the Vpp voltage high enough? Does it rise quickly enough from 0 to
Vpp?

Wouter van Ooijen

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