Pulse Clock, Part One.

By nuff
July 31, 2023
3 min read


(Spent two days trying to get the LED ring to work without any discernible progress)

Moving on to pulse sensor - this ended up being fairly straightforward. Using Pimoroni Max30101 checked out from the shop (explain what it is and how it works). Installed library, wired up the sensor, ran the example code (there's one provided that includes an algo for getting an averaged heart rate, which is exactly what I need). OK, now that I know that works, I'll put it to one side for now and reintegrate once I can get my lights going.

Decided to try an Arduino Uno—it's 5v by default vs the 3.3v Nanos I've tried so far. At first, no difference. As I was about to give up, Nun (one of the residents) walked by and asked how I was doing. After talking for a few minutes, she inspected my circuit and decided I probably didn't need the resistor (which was recommended in the Neopixel library to not burn out the lights). That got some sign of life for the very first time since I bought the LEDs in 2022(!!!!!). However, only one quadrant of the 4 was working.

Nun suspected it might be because I'd joined the whole ring all the way round and asked for permission to resolder my sloppy work. Watching her work levelled up my soldering game in 15 minutes more than I probably could have in a year on my own. Some major tips I learned:

  • Tape things down if you don't want them to move as you work. Gaff tape works perfectly for this
  • Use flux paste to protect the electronics and plastic parts from the heat. This also works really well as a "holding goo" for the little strips of wire (I'm going to have to explain the wire bridging part of this somewhere)
  • Keep your soldering iron properly tinned as you work. This involves applying a small amount of solder to the tip of the iron. A well-tinned iron is a lot easier to work with
  • Apply some solder to the wire, then place the wire, then apply a tiny bit of heat to reactivate the solder. use pliers (or something similar) to hold down the wire with your non-iron hand.
  • Honestly, the plier thing is such a game changer I'm ordering a set of my own.

I can't explain how much better equipped I feel for soldering/electronics work than I did on Wednesday.

Hashtag PComp

Sometimes, you've done everything right. Your circuit is perfect, your soldering flawless, your code exactly matches the reference. And yet things don't work. The number of times you can solve this by a) wiggling something b) pinching something or c) reattaching something is frankly terrifying.


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