Sunday, December 5, 2021

Christmas Tree Project Step 2: The Lights

Last time, we left off with all supplies gathered. Now, it was time to wire things up and get the lights lit up in some pretty colors. First, though, I had to solder headers onto one of the breakout boards. Soldering isn't something I'm great at, but this seemed like a manageable task.


With that behind me, I could start wiring things up. My first try was to just connect the power wires to the lights. But the result was nothing. However, I didn't know if this was because I had made a mistake, or that they just wouldn't light up until there was a data signal telling them to do so. So, I took out a Raspberry Pi that wasn't doing anything at the moment. After spending way too much time on things that should have been simple (like trying to configure wifi on a device that doesn't have wifi), I managed to get things up and running.

Here, I used a little bit of a trick. In order to make it work. In order to make two power supplies work together nicely, you need to wire up the Grounds. However, the Dupont cables I was using didn't have an easy way to go from the breakout board to the lights and to the Pi. However, the Pi has multiple Ground pins, which are wired up internally, so I connected the Lights to one of them and breakout board to another, basically letting the power flow right through the Pi. Unfortunately, nothing happened yet again.


Still nope

Now, it was time to do some debugging. I wasn't even sure if I had gotten the right one of the two connectors, so I messed around with that for a bit, but to no avail. Then, I realized that I could just get rid of the power adapter and breakout board for a bit. As long as the power draw wasn't too high, powering the lights from the Pi's 5V rail shouldn't be a problem. And indeed, I got things to light up!

My one LED program works

This meant that the Pi, the code and the wiring were all good. The problem had to be in the adapter or the breakout board. I should probably have gotten out a multimeter and started measuring. I decided to try something else: powering the Pi from the breakout board. This could definitely potentially damage to Pi, I went with it anyway. And I did see that the Pi's power LED only powered up when I was touching the ground pin on the breakout board. Apparently, I had done poor job soldering and there wasn't a good contact there...

Green across the board!

After making sure the soldering job was done properly this time, I hooked things up again. And I got the lights to turn on this time. It seemed that the hardware part of it was done now. And because programming is what I feel comfortable doing, I was quickly writing several effects. These weren't actually getting me closer to my Christmas tree goals, but I liked doing it nonetheless.

The effect that I liked the most was one that picked a random color for the first LED, and another color for the last LED without changing the last LED just yet.  Then, it gradually moved through the lights in the order of the wire to turn them a color that was slightly closer to the color for the other end each time. Once done, it would pick a new color for the first LED, and do the same thing on the way back. I wanted to include a video of that happening, but the effect didn't show too well on video and there were also some interference patterns causing lines of darkness. So, instead, a picture of each LED in a different random color will have to do.

A poor substitute, I know...

Next time, I suppose I'll have to start involving the actual tree.

No comments: