18F4431 and Melabs USB programmer ?

[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.
<br>

[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?
<br>

[AndrewC]

Hi Darrell, yes - erase before programming is on. If I read the device after erasing it comes back as 3FFF's , Meprog also correctly recognises the device as an 18F4431,

The programming error I get seems to flip between 0000 and 0018. It seems that sometimes it manages to start programming and then gives up after a few words.

I do have the original USB programmer. My dilemma now is trying to decide:

1) Is it the PIC itself - in which case I might try my luck at complaining to Microchip and getting some replacements.

2) Is it the programmer - in which case I need to decide whether to go to a U2 or a PicKIT

3) Is it the user - in which case I'm going to go and chop up some wood on my bandsaw and then spend several hours planing and sanding it and getting back into equilibrium with my inner self. Or have a few beers and a curry

Thanks for your persistence in trying to help me

Andrew

[mister_e]

Try few 0.1 uF + 10uF tantalum close to your pic when programming. If you have 2 Vdd, then you use 2 0.1+10uF. PGM pin load to gnd with <10k.

Try to measure the MCLR line, and see if it's high enough... >12 V at very least.

I already had some weird issue in the pas when the PIC programmer was too close of the PIC... weird, but happen.

[AndrewC]

"If you have 2 Vdd, then you use 2 0.1+10uF. PGM pin load to gnd with <10k."

Not sure what you mean - on the Melabs USB programmer there is only one Vdd supplied, i've already got a 0.1uF across that on the programmer board. If I try programming it in-situ on the Melabs X2 protoboard I can use it's own Vdd and it also has 0.1uF Vdd-Vss next to the PIC. Where would you add 10uF ?

I've tried tying RB5/PGM to ground with 10k, perhaps I'll try something smaller.

MCLR is going to 13.2V

Spacing to programmer - I've seen some posts pointing at this. I'm using the short cable supplied by Melabs (<1" ?). I can try making a longer one

My biggest headache is "is it my programmer or my PICS ?". If I could be sure that the U2 programmer works with no problems I'd buy it, or the PICKIT 2, but no answer from MELABS yet. I'll email them again in case they overlooked my first three emails.

Micro chip pointed at the same note the Darrel posted - try playing with different Vdd values but could not tell me what to try and Vdd is not adjustable (to my knowledge) on the Melabs programmer. They didn't seem to buy in to my suggestion that 60% of the PICS they sent me were cxxp and they should give me some new ones. Of course I only bought 5 so I'm not very high up on their priority list

What alternatives would you recommend to using the ICSP serial type programmers ?