Smaller is always better, right?

 The great big 2ft square boards were fun to build - and when they worked, they were impressive to behold! But building and debugging them was a real pain! And getting the boards cut to exactly the right size could prove problematic (not everywhere has a local wood merchants with a laser-guided table saw that can cut to within 1mm).

Already we were considering how people would make these at home, or in a local hackspace/makerspace, or using common tools (like a laser cutter or a cnc router).

2ft square boards were just too big and cumbersome to be DIY-friendly.
So we looked into 12" square 8 x 8 grids...


Yes, in order to create a 2ft square board you'd need to make four of these, instead of one large board. But the amount of wiring was about the same. And it's just far, far easier to debug a smaller panel

The smaller size also meant we could easily laser cut the MDF on an A3 laser cutter.
In fact, with a little clever gluing, it was even possible to make the board out of two smaller sections, and laser cut everything on a cheap K40 A4 sized laser cutter - something readily accessible to many "makers".


While we were fully embracing the "make it yourself" open source hardware route, instead of trying to produce these as retail products, we thought it was time to consider the ultimate "DIY-hacker" platform.... Arduino.


One of the upsides of using an Arduino (Pro Mini) as the microcontroller, instead of a PIC, was that each i/o pin could now both sink and source up to 40mA.
It turned out that this was just enough to power an entire row of eight hall effect sensors at a time.
While we'd still be multiplexing to read a full array of eight sensors, it massively simplified the actual hardware/wiring - no more source drivers or shift registers, or custom PCBs with custom-assembled surface mount components; it was now possible for anyone with a soldering iron and an Arduino Pro Mini (and a bunch of hall sensors and some copper tap) to make a working board, without any additional hardware!

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