Week Review 4/25/2024

Introduction

This week and during vacation the robotics team made a lot of progress. Ben and I were able to get the float in the water and operational. We now just need to make some finishing touches and get the depth sensor working. The float now is able to communicate over WiFi, sink, then float.

Electronics Changes

By far the largest changes that we made we electronic. We did a complete overhaul of the PCB, replacing both the microcontroller and the motor driver.

I had an overcurrenting issue with the motor driver I was originally using. I decided to switch to the md10a motor driver because it had a higher current limit. Unfortunately there is some kind of feedback that comes back through the input pins on the motor driver that the Adafruit QT Py is not able to filter out. Whenever I would run the motor the microcontroller pins that were connected to the motor driver would die. After checking on an oscilloscope there were voltage spikes on the input pins of the motor drivers from motor noise. The Adafruit QT PY is so small that it can not fit the voltage protections on the board that a larger development board would be able to.

The simplest solution to that problem seemed to just switch to a larger microcontroller. I decided to use the Adafruit Feather because it uses the ESP32-S2 Microcontroller and there is a relatively straightforward hack to use an external antenna.

I remade the PCB and the float started to reliably work. To use an external antenna I followed this guide to scrape away the soldier mask, sever the connection to the rest of the antenna, and solider to the scraped away mask. To my surprise it is actually a fairly straightforward process and the external antenna works reliably.

Documentation

The documentation due date is fast approaching so I added some finishing touches to the float documentation that I started in October made a System Integration Diagram for the float (SID).