ELECTRONICS

Our goal with the electronics subsystem was to create something that was highly capable while being reliable and easy to set up. For that reason, we elected to use off-the-shelf breakout boards. Our two batteries in series provided the 10-20V for our motors and our voltage regulator. The regulated 5V powered our encoders, ultrasonic sensor, and Teensy; the 3.3V from the Teensy then powered our line sensors. Because our encoders and ultrasonic were 5V logic level, we chose the simple method of using a couple of logic level shifters so that our Teensy could read them (and trigger the ultrasonic), sticking to our ethos of breakout boards and simplicity over building voltage dividers or other custom circuitry. Our limit switches (originally two, but the upper one broke and our arm was reliable enough that it was deemed too unimportant to replace) were wired in what I might call a "3D printer style," with the NC connection used. That way, a bad or unreliable connection would result in a false positive rather than the arm ramming through its endstops in a mad rampage.

Our wiring was largely done on breadboards, with the exception being the VBatt power rail, which we soldered into Adafruit perma-proto so that our power rail was as reliable as possible. We also found that the extra pins on the Teensy 4.1 were worth the relatively low price, compared to the headache of getting two Teensy LCs to talk to each other without missing encoder counts or other weird implications of blocking serial code.