The interactive schematics and gerbers are subtle but very effective.
Overall a very clear design and tone I really need to follow for my own PCB projects.
Do you have any books you recommend on electronics? I feel I understand the basics, like what various components do in isolation, but would love to level up and understand circuit design like how you are approaching it here
I can recommend Practical Electronics for Inventors as a solid base of projects to experiment with and learn from. If you want to learn how to improve circuits and optimize for specific behaviors, there is a wealth of information in manufacturer application notes. A lot of the protection circuitry used in my article follows advice found in application notes.
Do you prototype all this on a breadboard before making the PCB and picking specific parts? I'd be curious to hear more about your process. I feel like I always need to test everything I build on a breadboard first since I inevitably miss some small detail if I go straight to schematic + PCB design.
If I'm pretty familiar with everything, I generally dive into a rough PCB layout and debug from there. If I absolutely can't get anything to work, I'll go back to the drawing board and possibly do some little breakouts, for example: https://twitter.com/theavalkyrie/status/1457845661370568709
Edit: for this specific project I did make breakouts for testing the MOSFETs and solenoid drivers. I'm glad I did, since I was able to try out a couple of different options for each: https://twitter.com/theavalkyrie/status/1550878465876004865
One thing I wanted to add - I recommend placing a large-ish cap (22u) when using ferrite bead\inductor, as you can get ringing/oscillation otherwise.
I got to the part about 3.3V being derived from 5V and thought to myself "why not get it from 24V?" and then just a tiny bit later, there's the bit about USB and how Starfish can just take 5V from the USB host, and it clicked.
I also learned about Sparkfun's QWIIC connector in the aside about the chosen i2c bus switch having two "extra" channels. Love it, thanks for the article, Thea.
> why not get it from 24V?
There are DC-DC converters in that same family that can do 4.75~36V -> 3.3V, but since I needed the 5V anyway for the LEDs and I/Os, tossing an inexpensive and small LDO for 5V -> 3.3V is an easy call.