Commodore 64 – SID in AVR wrapping

… or a story how I suck at choosing the proper file

The story

Once upon a time, there was a little pony called Bungholio …

OK! OK! Wrong story. Let me start it over again.

Fried 8580

It all started as a fun project. My fellow group member Johny of Lamers asked me if I could make a hardware replacement for his fried SID 8580. He sent me a link to a website with an awesome project – SwinSID – It was created by Swinkels (Cheers mate!).

http://www.swinkels.tvtom.pl/swinsid/

Challenge accepted!

Homemade PCBs

I’ve started with one of the early versions of SwinSID, more precisely SwinSID SE.
I chose it because it required easy to solder THT components and
it had simplified, one-sided version of PCB.

It was supposed to be a totally homemade project so I’ve decided to go with toner-transfer method …. like in the ’90s 😀

First, a step required printing layout in a proper size on a paper coated with a mysterious substance.
protip time: This special paper can be found in nearly all homes nowadays, most probably near a toilet throne, so the king can read while “ruling” his kingdom lol. It is simply a paper from color magazines – the thinner, the better. All you have to do is to cut a few pages out and print on it a PCB board layout with a Laser printer.

Next, you have two options. Either go with iron like in the ’90s …. or buy a cheap laminator and hack it to suit your needs. In my case, it was, of course, laminator. The hack relied on removing overheating protection and changing few resistors so a laminator could run at higher temperatures. Also cutting out unnecessary parts of the plastic case might be handy for larger PCBs

Now armed with a “pro” tool, I could proceed with toner-transfer by simply pushing a blank PCB with a taped-on printout into laminator (HINT: use Kapton tape). Just a few passes are needed to transfer toner to PCB. Then I put it into the jar filled with water and after a few minutes, I was able to slowly tear off a soaked paper. I was ready to etch my PCB. For etching I use Sodium Persulfate – works like a charm.

Here is a result.

Finally, I could solder on some parts.
Here is a photo of nearly complete PCBs.

And here completed PCB with all components populated

Burning firmware

Having done that, I’ve started to burn firmware on an AVRs – in this case, ATmega8515.
Here is a quick hack that I’ve created for this purpose

Programming is done via USBasp dongle

However, instead of the proper SID tune, I was getting squeaking sounds.
At first, I’ve thought that I’ve burned wrong fuse bits – nope.
Later, that may be the wrong components – nope again.
I’ve checked everything 10 times. Also, Swinkels suggested that squeaking might be caused by using wrong DAC so I’ve ordered new DACs – TDA1543 (not TDA1543A) – still nope.
In the end, It turned out that I was using the wrong firmware file all the time…

But I finally got it working! YAY!

AVR implementation of C64 chip – SID from pit on Vimeo.

So yeah, that all worked fine and a project was really fun but that is not the end of the story yet :>

Going “PRO”

SwinSID SE is very nice but SwinSID NANO is nicer!
Unfortunately, NANO is a bit harder but still doable if you know some tricks.
Nicolas Welte of x1541.de did a great job and scaled-down the original SwinSID project to a SID chip size. I’ve contacted Nicolas and he gave me a green light with using his board layout.
Thing is that this layout had to be machined on professional CNC tools.
I only have a small, homemade PCB router which is for prototyping purposes and has some limitations. (it will be covered in another post)
Sending projects to production requires modifications according to manufacturers guidelines, so I had to apply a few changes.
That wasn’t too hard and after several days, I received a package with nice and clean PCBs. Big thanks to Willy of Lamers for hints about PCB manufacturers.

ZOMG ! some soldering skillz needed

First things first, in this case, it means soldering MEGA88PA chip on a PCB.
It might look hard to do with a simple soldering iron but in fact, it is quite easy if you have thin solder, good flux, soldering wick, and steady hand 😉
Here are few PCB with chips already populated

Using a cheap USB microscope turned out to be very helpful for doing the proper inspection afterward.

Firmware

This time, I’ve double-checked if I have proper file 😀
As you can see there are 6 small vias which are used to burn firmware to freshly soldered on MEGA88PA.
This actually required creating an awesome piece of engineering with a wicked name – The Connector.
It was made out of desoldered SATA port, few wires, a bit of epoxy resin, some bee wings, and zombie poo.
It looks like this:

Let the burning begin!

BOOM and it worked out of a box …. to my surprise

More soldering

Again, not so hard after all but I definitely do not recommend soldering it after few heavy shots. Unfortunately, it turns on specific video effect called – Motion Blur and it lasts till the next morning, so be careful ;>
Components that have to be soldered on are simply five SMD resistors, one capacitor, pins and a bulky clock generator which additionally serves as a radiator to MEGA88 chip.
This is how it looks in its final form.

I’ve made quite a few of these and will be most probably selling it.
No worries, I’ll create a link to a store on my main page soon.

Testing

Finally here is how it works … and yeah enjoy this TekknoChipTune 😉

Nano SwinSID – Testing complete ;P from pit on Vimeo.

Cheers 😉

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