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Solder me up, Scotty!

A project log for Tap to control

A small, ESP32-Pico based wearable for everyday DIY Smart Home control

xasinXasin 10/21/2018 at 14:220 Comments

So, the parts finally arrived!

Last Wednesday, actually. Delivery time was a week or two longer than expected, but for the price of production and shipping, I'm not complaining.
Regardless of this, the quality of the PCB and solder paste stencil was excellent, and I quickly found myself stuck behind a soldering station for a few hours to finish up a first revision.

To my very pleasant surprise, I was actually able to complete the entire solder in a single day! It's a small board, but still ... Thanks to my University for the hot air gun ;)

Booting it up was definitely an exciting moment. I don't know about you, but holding a 300°C airstream onto such a delicate chip like the ESP Pico and hoping everything aligns without ground pad shorts or such ... Stressful.

Long story short, the entire chip worked first try, and I was able to upload the test code I had prepared without problem. Within a few minutes I had the built-in WS2812b glowing in lovely colors, and it seemed more than happy to run off LiPo power too!

I noticed that the ADC reading of the battery was off though - it kept maxing out whenever I had left the USB connection on for a while. It wasn't until I checked the Charge Status pin of the LiPo charge controller that I noticed it was drawing the line up to 4V when done, not just 3.3V!!
I had to cut the trace there to prevent further damage to the ESP, but apparently it survived perfectly fine. Always a pleasant surprise!

Then, I could finally set it into the printed shell, together with its LiPo battery. Have a look - I think it turned out quite well!

IT GLOWS - WS2812b at full power!
The center light is a addressable RGB LED, and has in-software color fading. Looks neat, eh?
"Please state the nature of the medical emergency" will be my new "Hello" while wearing this, I fear

I can't just give good news though. The ESP library apparently has a problem with putting the chip into light-sleep mode while the BT controller is enabled (even when it's idle), which means there's a constant ~20mA draw. This'll limit the runtime to about 10h with the 350mAh battery, but I'll try manually disabling the BT controller or forcing sleep mode.

Aside from that, we're all set for the next stage - setting up an App and a permanent BLE link!

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