Wireless Reprogrammable PS2 Controller (Part III)

(or how I came to ditch veroboard)

Okay…

So, in the last post, I was about to build a vero-board model of the WRPC, having successfully demonstrated proof of concept on breadboard.

The reasons I chose veroboard for the next phase was that:

1. There are a lot of pins on microcontrollers and my drill press isn’t compatible with the 0.8mm bit.
   (read that as: I don’t wanna hand-drill a billion holes)

2. Less effort than a custom PCB

Point B became more than arguable over the course of development, as you’ll soon read about. For those of you either not on Google+ or just not reading what I post (fine, then!), here’s how the progress reports went:

Drama - Act 1, Scene 1

One fine day on Google+…

Later…

Finally…

Why did it fail?

The veroboard approach failed because either:

1. I somehow made the tiniest little melt or jumper or something but because of how immensely complicated the back of the board became (because I wanted it to look nice), diagnosing it became impossible (but I still tried).

   OR

2. Nothing was wrong with the veroboard, even though diagnosis was impossible. There was a mistake in the breadboard to veroboard conversion.

As it turns out…

When I finally caved and rebuilt the breadboard circuit with new parts (I will desolder and harvest the veroboard later), it did have an error. It didn’t make much sense to me at the time (and at time of writing, I’m just accepting it for now) but somehow connecting the second ground pin on the Atmega when pin 8 was already grounded caused an issue with reprogramming the board with the Wixel. If you’re interested, compare the schematic from the original post with the one below.

What I learned (VERO == UGLY)

Only use veroboard for circuits that will be out of sight or those that you don’t care how they look. If you try to get clever and reverse-wire a vero, it will only come back and bite you in the arse.

Onwards and Upwards

Once I threw out the vero idea, rebuilt the breadboard (and spent hours tracing down the source of the error), I was ready to arrange the PCB. After a few hours of rework, here’s the completed design courtesy of Fritzing:

Smaller than the vero model and much sexier.

I have included a full set of breakout header traces for both microprocessors and space for two stabilizing capacitors on the regulator, should I desire to add them.

Press-n-Peel

Now, the main reason I wanted to avoid a custom PCB for a prototype in the first place was because of all the dicking around with transferring a design to the board itself.

To that end (and because UV boards are bloody expensive), I bought some Press-n-Peel film from techniks.com. I have tried several different ways of PCB transfer, but I will have to say that provided you’re willing to do a bit of trial and error (like any method) with your printer settings, iron heat and method, Press-n-Peel film will give you the best PCB-making experience for your buck.

It took me 5 attempts to work out the correct combination of printer setting, iron heat and method but after those five attempts, I had this:

You’ll notice some minor touch ups because for this one (funnily enough) I used an imperfect piece of film. Murphy can eat my shorts as usual. Anyhow, it was only a short, soft scrub from that to this (custom type/art was added post-Fritzing in Inkscape, but more on that later):

And after all the etching and glazing…

…and all the drilling work (which I’m not that good at by hand) I realised…

…that I’d printed the bloody thing out BACKWARDS.

Well! Isn’t this just a full-on bag of …. F…un ….

Nevermind.

While it did massively increase the complexity of the soldering job (I soldered the microcontrollers on the reverse side) and changed the overall look of the finished board, I still managed to pull it off without losing it (somehow). I even held it together when my soldering iron died in the middle of it (I fixed it again).

The final (hardware) product

After this very very long and dramatic journey, with more twists and turns than I could even be bothered writing about (yes, there were more), here it is - the finished hardware:

Afterthoughts

I have written myself a reminder to do this, so I’ll get to it when I can spare another moment… I am going to post the settings that worked best for me with the Press-n-Peel film because I didn’t find that many articles that were very helpful about it online.

Until then…