9/21/23-9/24/23: Part Printing Complete!!!, Linux Commands, Serial Wombat

9/21/23: Part Printing Complete

9/22/23: Linux commands

Over the past couple of months, I noticed a strange pattern with the Octoprint instance: it seemed to be slowly and inexplicably running out of memory space. I tried deleting everything I could–all the cached print instruction files (Gcode), as well as all the stored timelapse videos and error logs. However, despite my best efforts, the available storage space steadily decreased.

As I was attempting to use the printer today, I learned that my Octoprint had completely locked up on account of running entirely out of storage space, as seen below. That meant that my only hope of saving the Octoprint instance without having to wipe it and start over was to use the PuTTY SSH connection to go dig deep inside the Linux command line and see if I could delete any extraneous files and get some storage space back. Thankfully, I followed some guides online and was able to successfully remove the extra 3GB of log files that were clogging my system, and now the Octoprint instance is as good as new!

Too many logs filled up my /dev/root file. 0 space left. Now, after the fix, it’s about half and half genuinely “good files” and newly available storage space.

“cd” command allows you to enter a directory.

“ncdu -x” creates a very handy wizard that helps you find the largest files in your system and delete them. I deleted all the log files that were using about 3 GB of space (all that I had left to use).

“pwd” allows you to see which directory you’re in.

“sudo” helps you have admin powers, I believe.

“su” does something similar; I understand something related to the root user.

“ls” helps you see all the subdirectories of your current directory.

“rm” helps you remove a directory or file; append “-r” or “recursive” on the end if you want to delete the whole directory and the stuff inside.

9/24/23: Serial Wombat

Today I edited some of the electronic systems within the plane to make it easier to edit, make the servos more accurate, and overall much better. I found a cool chip called a Serial Wombat earlier this month that I will use to make things a ton easier!

As seen above, the Serial Wombat is essentially a small microcontroller with a timer circuit that can time incoming digital signals or create consistent output digital signals. For an Arduino to do this, it either requires mastery of interrupts or takes up processing time that the Arduino needs for other tasks–vaguely important things some people may have heard of like “thinking”, “reading data”, or “sending other instructions”!

The Serial wombat will be a lifesaver for the project. Each chip can handle up to 4 inputs or 3 outputs, or any combination of the two. The way that I’m going to use the four Serial Wombat chips is as follows:

1. The first two chips will solely consist of input from the RC receiver. For now, this will only require 4 inputs: aileron, rudder, elevator, and the on/off autopilot switch, so I may consolidate it to 1 chip. However, if I want to add flaps or automatic throttle control later, that will be the best method to do so.
2. The second two chips will be for output to the servos. This definitely requires 2 chips, as each chip can only handle 3 outputs. I have at least 4 and maybe more output servos: at the very least, left aileron, right aileron, rudder, elevator. If I want to add throttle control and any flaps later, it will require more attention.

I also realize that I’m going to need to re-print the tail entirely before flight. It’s disappointing to have to scrub the launch for a whole week, but it’s for the best of the plane and the project. In the meantime, it’s back to testing and re-CAD-ing the tail! I would like to have something like a direct-drive gear system for the elevator and rudder, rather than the metal wires that I’ve been using.