James Thorpe

Matrix Blocks

Jan 04, 2019 electronics pic

In my first post after the website reboot, I said:

I'm also about to embark on some electronics projects, and I wanted to have somewhere to write about what I'm doing.

Well, here we go.

A few years ago, I built an LED cube:

It has an Arduino at its core, and some custom made circuitry on stripboard with various shift registers etc to control the cube itself. It was a fun build, and around that time I was looking at what else is out there that would be interesting to do.

I came across the GLiP project, then quickly also found its successor, MB Led:

I liked the look of the Cube World toys back when they were a thing, but never actually had one. Needless to say - the MB Led blocks interested me a lot. Back at that point, I didn't really have any knowledge of using microcontrollers beyond the Arduino, and also making up some kits that use preprogrammed PICs to control aspects of a model railway (those kits being from MERG) - it was all a bit of an unknown world to me. Stripboard would also have to go to make things small enough; the price of getting PCBs manufactured was another showstopper. The idea has kept resurfacing and bubbling in my mind the last few years.

Fast forward a few years, and a bit of research on my part; designing circuits to hold a PIC and the subsequent programming of it no longer scare me like they used to. The price of getting PCBs made is now also seemingly dirt cheap from the likes of JLCPCB. I've not yet tried them, but I've heard some fairly good things.

One sticking point on cost seems to be the infrared transceivers needed for inter-block communication - they seem to be around at least £2.50 each, which would add £10 to the cost of every block. Instead of this method, I'm looking to see if I can instead perhaps use some form of magnetic connection between the blocks - essentially connecting ground and the Tx/Rx pins of each PIC UART directly, though I'm also still investigating the IR side of things to see if I'm missing something there.

Rather than having each block directly host the LED matrix on top, I'm planning a slightly different approach. The idea is to make a "common" base which handles power, inter-block communication, general processing etc, with two rows of headers exposing power and plenty of GPIO/SPI/I2C etc. Different attachment boards can then be made - one would be an RGB LED Matrix with the circuitry to drive it (with another PIC "GPU" on there if necessary), but I'd also like to have blocks with controls on - push buttons etc.

However, I fully recognise that I need to be able to crawl before walking. Today the order went in for a PICKit 4 (glad I waited - the price dropped around £10 over the holiday period, which is nice!), a few PIC18s, a bunch of LEDs (I have plenty of blue ones left over from my cube build, but no other colours) and some new breadboards to put them in.

Hey, I've made a nifty logo to put on the PCBs already though!

Hopefully the next post will see some programmed PICs and blinking LEDs...