Quite a lot has happened since the last update to this blog. First, I revised and fleshed out the design of the electronics in much more detail. More importantly, I finally began implementing certain parts of the electronics in real life. I also made some more minor additions to the CAD.

Firstly, I put much thought into how all the electronics would fit together, with specific components in mind. I started by identifying affordable options for the rest of the components I would need. I started with power for the key electronics—the Pixhawk and Pi. Because the motors I’m using are on the more powerful side, requiring around 22V; the minimum size battery pack I can use would be a 6-cell battery that provides this voltage. However, both the Pixhawk and Pi require voltages of around 5V, meaning connecting the 22V battery straight into them would most definitely fry them. The solution is an intermediate device that steps the voltage down to accepted levels; I found cheap options for both: a power module splitting off a 6 pin connector, perfect to power the Pixhawk, and a 5V step down converter with a USB-C connector for the Pi. With these components established, I made a slightly more indepth (still hand-drawn) diagram of all the electronics, starting from the two 6S battery packs in parallel going all the way to the ESCs and the connection to my computer. 

I also began setting up the Pixhawk and Pi to control the actual drone. Firstly, with the Pi, I followed the PX4 guide on how to set up the Pixhawk with a companion Raspberry Pi at https://docs.px4.io/main/en/companion_computer/pixhawk_rpi#wiring. I started by flashing Ubuntu onto the Pi, then establishing an SSH connection between the Pi and my main computer so I don’t have to connect a monitor with the Pi to use it. I obtained some female jumper wires and spliced them together with a 6 pin wire creating the physical connection between the GPIO pins of the Pi and the TELEM2 port of the Pixhawk. I then promptly ran into some issues installing the MavProxy software that connects the Pi and the Pixhawk likely due to my SSH connection, and I didn’t feel like going through the trouble of connecting an external monitor again, so that’s where I’m at right now.

I’ve also assembled one of the battery packs by soldering nickel strips to connect the cells in series. I 3D printed a couple endcaps that would keep the loose cells rigidly in place, as well as a snap-on connector that should be able to hold two battery packs together. This is what it looks like right now. 

However, I realized that it would probably be a better idea to completely enclose the areas with exposed wiring, and I also remembered that I would need to solder balancing leads onto each of the nickel strips, so I designed a new, closed endcap that creates a little extra space on each end for the balancing leads and also has just enough space for the actual battery leads and balancing wire to poke out. 

Finally, in terms of CAD, I decided I didn’t really want to think hard about the lighting, so I found some small, waterproof battery powered LED lights intended for like fish tanks or something, which I would just be able to slot into the front of the drone to provide a light source in dark conditions.