New Crystal Board Lives

I’ll keep trying to form this habit. Anyway, the crystal/portal game went reasonably well last year. A major problem was magic crystal assembly. They just took too long to assemble. I think it took me two long days to assemble six units.

This year I’m revisiting the design with a DFM focus. The goal has been a single PCB, nearly all SMD, instead of three PCBs connected by twelve separate wires. Crystals will now only perform IR comms from a single side, the bottom. The original crystal MCU was an ESP32-C3. Time was so tight that I never got around to writing radio code of any sort whatsoever. I didn’t miss the feature. So, I’m porting to the ATTiny3224.

That new PCB has now under gone a basic commissioning test. IR comms, the LEDs, and the UART are all working!

In contrast to the radios, the loss of the ESP’s RMT peripheral was actually a bit of a challenge. But I persevered and managed to get code for the Tiny’s Timer B working for both IR detection and transmission. I’ve been able to test IR with an olde ESP board with positive results. You can see the LEDs working.

The only thing left to test is the soft power. That needs a spot of code to work, but my bread board mock up looked good, so I’m hopefully it is all fine. (In the photos I’m supplying 5V power directly past the soft-power/v-reg stage) The “simple” push-on-push-off mechanical toggle switch I used for the old board was actually a PITA to setup requiring three wires all it’s own.

Another thing to test is the new omni-polar Hall Effect switch. I didn’t know that was a thing last year and lost a number of plastic shells that had the magnets glued down in the the wrong orientation for my directional Hall Effect sensor. Now it shouldn’t matter what orientation the magnets are in. Again, bread board tests of this device were positive and I am excited to try it out in a crystal with all the mechanical details. (Two layers of plastic, magnet to sensor, alignment, and whatever else comes up). But I still need to redo the lower cap to accommodate the new SMD parts.