Hi all!  I've been off the list for quite some time now and it's nice to be
back :-)

To the point...

There was something wierd the orther day about my 16F628 based prototype...
I could simply not get the thing to execute code!
After going through all the docs again I still hadn't found what was wrong
so I did something that shouldn't have solved the issue according to specs.
I tied MCLR to VDD *even* if it was already tied to VDD internally.  (Yes, I
had disabled it because I didn't need it, and I was using LVP ICSP.)
Now, everything worked as it was supposed to?

It doesn't say anything in the docs or programming guide that even when you
disable MCLR, you need top pull it high during startup to avoin entering
programming mode...  But that was what was happening!
Either that, or some limbo-state occurred.  I'm not sure about this as I
measured on the pinns while in this state, and some of them had 1.8v 2.1v
and 3.2v on them, and they were actually not attached to anything???
(Floating)

I had previously made up a SCHAER compatible programmer that used MCLR av
VDD control so that it would be compatible with LVP.    I did this based on
the info in the programming doc where it shows how to enter programming
mode.  Now I have adjusted the programmer a little more and so it will now
do LVP ICSP with the circuit wired with MCLR high or pulled high.  It even
works with ic-prog :-)

Oh'well...  Turned out that a wierd little glitch stopped me dead for many
hours...

I'm posting this here, now, because I want to know if I misinterpreted
anything in the manuals or if others may have similar problems.  I have
already searched general usenet and the piclist archives without finding
anything, and so this might be helpful to others in the future...

Oh, and if anyone is interested, I might post a schematic and PCB of the
little programmer i made on my homepage...  It uses 3-wire only +VDD/VSS and
does LVP mode only.  The whole thing fits in the DB25 connector and attaches
to the LPT-port.  (This might beling in a EE: but I'm to lazy to write 2
posts...)

Just for the search engines in the future:
On the PIC16F628, MCLR have to be pulled high during startup, regardless of
wether it is enabled or not to avoid entering programming-mode or some other
limbo-state.

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