Engineering / Minutiae · May 15, 2007

Electronics – or why I don’t hate Mondays

Isn’t this a neat sight? This is what was waiting for me this morning. The first-run prototypes of the board I designed last month arrived on Friday, so I spent part of Sunday, and most of Monday preparing them to be turned on for the very first time. And I have another day or two of work ahead of me.

My board is designed to plug into a system motherboard, and since that motherboard is designed by another team and weeks away from completion, I’ve got to ‘fool’ my board into thinking it is where it belongs. Hence the current wonderful mess you see here – I’m creating a ‘test jig’. (click to see the whole photo)

If I do it correctly, I’ll prove that the basic concept works as I expected, and will then be able to move into the programming of the on-board microcontroller.

And I’m really happy with this particular little microcontroller! It is a Microchip PIC24FJ32GA002, which I know means very little to my regular readers. Using a car analogy, I would compare it to a dune-buggy hot rod. Street legal, full of power and ability and very rugged.

Also Microchip did a couple of neat things with this little device. They modified their standard Harvard Architecture into something that is optimized for a C compiler so that I can program it using ANSI C. They also jam-packed the device with specialized peripherals to allow me to use A/D converters, multiple communications protocols, Pulse-Width Modulated outputs, infrared communication and more. All of this into a chip with only 28 pins. And that is the neatest part of it all – the device is part Field-Programmable Gate Array – I can reconfigure which pin connects to which peripheral in software, in real time.

I’d have to stretch that dune buggy analogy to give it a dashboard full of indicators and peripherals, all in a buggy that could be reconfigured at a touch to allow driver to enter and exit from any door he wanted, including the trunk, with such reconfiguring happening seamlessly while he was jumping sand dunes.

This is the fun part of electrical engineering, (or of any “Make“) watching something you designed start working for the very first time. I know that my first attempts will falter – but it will eventually work. Perhaps I’ll find an error in my design, or more than one. This is only the “first run” of this board, so if there is an error I will correct it in the next revision. In which case the current version will be scrapped.

But if that happens, don’t feel bad for the lost little microcontroller. I have a robotic dog on my bench at home that would be perfect for this device. My little robot doggie is looking for some new braaaaains!

So it’s back to that old grindstone, soldering iron in hand, headphones on and listening to Skepticality, or Freethought Radio, or Point of Inquiry, or Seth Shostak. It’s no wonder I work late, and on the weekend, when this sort of fun is to be had!

Oh, sorry. I meant, “stupid Mondays.”