18F4431 and Melabs USB programmer ?

[Darrel Taylor]

Do you have anything on RB5/PGM?
If it's left floating during programming it can cause problems.

A pull-DOWN resistor will help if it's floating.
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[AndrewC]

Hi Darrel,

I meant to mention that I had tried that as well.
So the analogue supplies are connected, I've tried with MCLRE_ON and _OFF, I've tried with RB5/PGM pulled down to Vss. No joy.

There seems to be a lot of noise floating around the net with people having trouble programming this PIC.

It looks like I might be having to give MC some money

Andrew

[Darrel Taylor]

Have you tried the latest version of meProg?

http://melabs.com/support/progsoft.htm (4.3 with firmware)
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[AndrewC]

Yup, 4.30beta and upgraded the firmware to meup54
The "volts" check in meProg shows Vdd = NA and Vpp = 13.18 when I "READ ACTUAL"

[Darrel Taylor]

I found this in the A2 silicon Errata ...
http://ww1.microchip.com/downloads/e...Doc/80180c.pdf

<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=3277&stc=1&d=123792998 0" />

Not sure if it only applies to the ICD2 or not. But the USB programmer might have a similar problem if it's an A2 chip.

A3 silicon doesn't seem to have the problem anymore.
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[AndrewC]

Sounds plausible, alas I don't think I can adjust Vdd on the USB programmer. What I might do is try and program it using ICSP on a breadboad with it's own power supply.

Andrew

nope - didn't work either

[Darrel Taylor]

nope - didn't work either

Bummer!

I was just reading Melanie's post ...
http://www.picbasic.co.uk/forum/show...1847#post71847

Thought hmmmm,
You have "Erase before Programming" turned on ... right?

So many straws to grab, not enough heads to make straw hats for.

Maybe time to break out my virgin 4431 from the parts bin, and try the U2 and PICkit2.
Do you have the original USB programmer or a U2?
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