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This is Kubik M0, a spider robot kit that I am developing that includes all the mechanical parts in its PCB. It's going to be programmed with CircuitPython, and it has a speaker and an accelerometer on board, with an expansion port for more sensors or actuators. I'm pretty happy with the mechanical design so far, but I still need to develop all the software for it.

At the Maker Faire Zürich we always had a couple of kids at our table playing the games, so they might be fun after all. Also, the devices lasted for 2 days on one set of batteries, and despite passing through so many hands and being dropped etc. none of them broke, so I think the design is actually sturdy enough. Next year I will hopefully run a workshop on programming them.

For Maker Faire Zürich this week I decided to try and let people control a MeArm with a PewPew. Got everything connected and the servos move, now to write the code to have them controlled with the buttons...

The pin header on the back fits with the mini-breadboards perfectly!

I'm also experimenting with adding some plastic or wooden parts to the bottom, so that it has a nicer shape and is easier to hold. For now just cutting them by hand, eventually they would be laser-cut.

The battery holders finally arrived, and the prototype is now complete!

So I connected the big matrix to the small PCB with some wires just to test if there would be enough current for it. Works perfectly fine.

Must. Resist. The. Temptation.

Who am I kidding, I'm probably going to build the big version anyways sooner or later, now that I know the matrix is there...

And now with the code updated to handle the new way of connecting buttons, which saved me 5 pins for connecting external stuff. (Sorry for potato-cam, it's dark in here already.)

The very first prototype of (top) next to the very latest (bottom). It has been almost 2 years. The functionality didn't change much, what changed is mostly the price — from over $30 to less than $10.

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The PCBs arrived from Elecrow and instantly I saw a problem — one of the traces is too close to a battery pad. Fortunately a quick cut separates them. Wrote the code for attiny13 to blink the LEDs, and it's now ready. A blinking hair clasp.

I let the design sit there for a couple of days, while slowly improving small parts of it. Finally I decided it's ready, and ordered in from OSHPark. I decided to make it only as high as the LED matrix, and make the pin header accessible only from the bottom — this way it's more robust and has better proportions.
I'm also considering designing optional laser-cut pieces to go on the front and back, to make it consistently thick and hide the battery. I will prototype those with wood for now.

Of course I would need a nice header for the pins, so that you can plug it into your breadboard or connect with jumper wires (none of that microbit edge connector nonsense). And since you want to keep the breadboard some distance from the computer, I need to drop that USB plug and use a micro USB cable. Might as well also switch to a more convenient horizontal layout, and use AAA batteries instead of AA, and... something like this, I guess?

I got my matrix-driving code modified for charlieplexing, and it seems to be working... This is my first charlieplexed display. Getting the PWM values correct for this so that there are 4 distinguishable shades is going to be some work, for now it's just blindingly bright, and the poor tiny coin cell only lasts a few minutes, so I connected it to a bench power supply instead.

Here is another version of the skull board, this time featuring Jolly Wrencher from Hackaday. I only broke out three pins, and one is connected internally to a copper pour to detect touches, but the optimizer in me suffers as there are 20 gpio pins going to waste, not connected to anything.

I guess I could throw a few of APA102 LEDs in there...

Switched to software PWMs on a separate timer. With some fine-tuning and timer magic, I have a stable picture with 4 distinguishable shades. No flickering.

Now, what was that game that I was supposed to be working on?