Elby designs PolyDac trouble

rumpofsteelskin · Joined: Apr 22, 2009 Posts: 46 Location: brighton, uk

Does anyone have the elby designs polydac? Anyone tried to program one with the files on the elby website?? Come closer and I will tell you a tale....

Mine worked fine until I had to re-program the chip. i used the files available on the website. After doing so - while it does work ok - I noticed that the CV outputs no longer work and when I investigated further I found that all the outputs to the multiplexer appear jittery - the frequency is shaking about so much that sometimes my scope can't get a lock on them. I assume that the inputs to the multiplexer are meant to be a binary clock with different divisions on each input to clock through the different outputs. I have tried to isolate the problem but as far as I can tell it's coming from the ATmega16. I tried changing the crystal, the chip itself and the opto-coupler but the problem is the same....

So at the moment I'm thinking it's a problem with the .rom and .eeprom files from the elby website.... I've sent them a message but I thought I'd check to see if anyone has tried programming a chip themselves? i tried to compile the files from the source code myself but it came up with tons of errors. I don't know all that much about digital so I'm hoping I don't have to dig through all of them

anyone?
P

Skrog Productions · Posted: Tue Apr 24, 2012 4:14 pm Post subject:

Hi

I have the polydac as well Smile

.

Tho i didn't prog, a chip,

i ordered the pcb & chip for my build , i remember i had some faults on first power up , after a few emails i got another programed chip sent over and it's been working a treat for 5 years now .

It's a great bit of kit for modular melody & 4 note poly .

Dave.

xpmtl · Joined: Aug 10, 2007 Posts: 122 Location: Brussels, Belgium

never had to program the chip too. can't help much Embarassed

TheProf · Joined: Dec 26, 2006 Posts: 141 Location: United Kingdom

You could have a problem with the fuze link settings. These control such things as the clock source, reset and 'brown out' response, etc.

If you look in the 'AVR Studio Settings' directory of the zip file from Elby, these are shown there. If you're using AVR studio, there will be a setup file for the Atmel programmers, otherwise you will have to translate them for the programmer you are using.

Just a thought.

rumpofsteelskin · Joined: Apr 22, 2009 Posts: 46 Location: brighton, uk

yep, I have all the fuse settings etc. already. It would appear that there's something quirky going on with my setup or the compiled files are faulty...

gonna try and port the source code form codevision to avr studio and compile it all again. Then we'll see....

TheProf · Joined: Dec 26, 2006 Posts: 141 Location: United Kingdom

I'm quite interested in this, because I have a complete, but as yet un-run PolyDAC I built. I'm in the process of doing the panel now, and I too will be burning my own chip, once it's ready to test.

If I get to the run point before you finish your port of the code, i'll let you know how I get on.

rumpofsteelskin · Joined: Apr 22, 2009 Posts: 46 Location: brighton, uk

well Prof that is very interesting.

I programmed mine with a AVR ISP mark II through AVR studio 4 with the eeprom and hex files form the elby website. I can't think why any of this would be a problem, but if you're using a similar setup it would be interesting to see if you have a problem with yours.... if you are using an AVRISP i'd recommend modifying the ten pin header slot for a 6 pin one that fits the AVRISP - I've got a piece of ribbon cable soldered off the board because I can't get the original header out!

when you program it, check pins 37-40 on the ATmega16 to see what i mean - they should be a clock for the multiplexer but the frequency of mine is jumping around all over the place.

I'm working on porting the code, but I'm pretty new to C so it's slow progress....

magman · Joined: Feb 04, 2009 Posts: 351 Location: Liverpool, UK

Have you by any chance had a look at the Vaco Loco site, as I believe Paul was the original designer for this unit.

http://www.vacoloco.net/synths/polydac/index.shtml

There might be a bit of additional info here at least.

Regards

Magman

rumpofsteelskin · Joined: Apr 22, 2009 Posts: 46 Location: brighton, uk

thanks magman! That version of the firmware doesn't work with the new elby boards as they have been updated, but I did manage see that the clock for the multiplexer (which is the same) at least works fine so it looks like there is a problem with the file on the Elby website or with my programming setup. Laurie form Elby has sent me a new chip so it looks like it'll get sorted one way or another

it's a relief since I was trying to port my code to AVR studio with "help" from some of the bods on the AVR freaks forum - some of the most condescending and downright rude people I have ever had to deal with. Sorry - just blowing off steam!

rumpofsteelskin · Joined: Apr 22, 2009 Posts: 46 Location: brighton, uk

well i got it sorted - turned out to be a problem with a loose cap - whoops. There is no problem with the Elby firmware

the multiplexer clock - for anyone who might be interested - does look jittery because it's run from an interrupt which is randomly triggered!

Skrog Productions · Posted: Fri May 11, 2012 9:12 am Post subject:

heh , cool that it's working now , it's always the difficult faults that take ages to fix .
Now you will be happily running 4 mono synths from a midi sequencer in time with drums Very Happy

Dave.