Buoy Electronics – *test mule*

Buoy - tempSensor - source-01.png

I hobbled together a “test mule” to streamline work on the buoy electronics. The test mule jargon is borrowed from the  automotive industry and typically refers to a prototype vehicle used for road testing which looks physically different from the production model – this is done to evaluate the performance of the vehicle without revealing the final exterior design.

I’m not concerned about revealing the final design of the buoy (no secrets there, pretty sure will be a yellow float!) but I wanted a bare-bones test platform to experiment with new features without worrying about integrating all the sensors and other bits. So I  stripped out the GPS, IMU, SD card and MEGA, and replaced it with the smaller nRF52 BLE Feather, 0.6W solar panelsolar charger,  LoRa module and DHT22 temperature sensor. Then I crammed everything inside a 3D printed container and put it outside. The container was printed in white PLA and coated with fiberglass resin to weatherproof it, hence the slight yellowish color. *We will see how this holds up during the foggy and moist environmental testing this week*

Buoy - tempSensor - source call out-01.png

*nRF52, not 95 like shown in the image- oops*

Now I can streaming temperature and humidity data to the base station in my kitchen while the test mule is outside in the backyard working away. Or, stream the data over the Adafruit app and see the data on your smartphone for debugging. The code tracks the number of data packets transmitted so it is easy to see if there was an error during transmision.

It may seem trivial, but I see this as a BIG ACCOMPLISHMENT – woot! I’ll see how long the battery can last and monitor if any data packets get dropped while the electronics live outside for the week.

Oh, and the base station saw some love too. It has a bigger antenna and some professionally installed electrical tape to provide all the necessary structural support. Gatta love tape.

Base station - call outs


Features that need to be added :

  • put the microcontroller to sleep in between sensor readings (10 second delay)
  • connect the base station to a Raspberry Pi and steam the data to a website
  • fix issue with signal interference, the BLE drops sometime when LoRa is broadcasting
  • add power monitoring hardware, to track solar panel output and microcontroller needs
  • add magnetic on/off/reset switch


All the example code and hardware is sourced from Adafruit – they are AWESOME! I need to clean up the code a bit before sharing, but when it is ready I’ll post the files on the downloads page. You can find all the other source files there also.

One thought on “Buoy Electronics – *test mule*

  1. Pingback: Basestation + Raspberry Pi | Open Source Ocean Data Buoy Project

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