----- Original Message -----
From: "Daren X"
Sent: Monday, January 05, 2004 5:43 PM
Subject: [PIC:] VIHH on MCLR doesnt put PIC in programming mode


> The PIC is definitely running when MCLR is at 12v as the LCD displays
> the intro message and rs232 communications begin.

I think John Power made a very important point.  !MCLR needs to go from 0 to
12 within a few microseconds without spending any significant time near 5
volts.  He suggests 1 us.  I'm not sure of that, but I know it needs to be
less than 4 us.  In moving from your programmer to the test circuit, there
are 2 obvious possibilities; 1) If there is a capacitor on !MCLR, it can
prevent you from getting up to 12 volts quickly and 2) if the lines from
your test circuit are longer and/or have higher capacitance, they can have
the same effect.

72/73 de WB8RCR    http://www.qsl.net/wb8rcr
didileydadidah     QRP-L #1446 Code Warriors #35

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