The intelligent buoy requires position marking and communication. To accomplish those goals, we evaluated different alternatives and selected the main components in the design.
For the first prototype we mostly selected breakout boards to perform the proof of concept as soon as possible.
We considered different alternatives that were able to meet the requirements and then selected the best one, because of its features or the cost (we want to design low cost solutions).
- Microcontroller: we selected the ESP32 DEVKITC 32D as the breakout board for this project because we wanted to perform Over The Air (OTA) updates. Having OTA can reduce the times that the buoy needs to be opened to access the electronics. The buoy needs to be waterproof, and will be sealed. Relevant alternatives that were considered: the LOPY IOT DEV BOARD.
- GPS: we selected the Adafruit Ultimate GPS. We found that it has been used before in buoys for position marking in the Open Source Ocean Data Buoy Project and the Drifting Buoy Project.
- Communication: we selected the RFM95W LoRa Radio because it provides an acceptable coverage and the technology facilitates the creation of a network were different buoys are streaming their position.
- Motor Controller: we will test servo motors in the release mechanism, and the ESP32 can create the required PWM. We also added the TB6612FNG MOTOR DRIVER BOARD as a backup plan, in case we need to use a DC motor instead of the servo motor.
- GSM/GPRS: we selected the DFRobot SIM7600CE-T 4G(LTE) Arduino Shield because of its global coverage and the possibility of incorporate 4G GSM at a relative low cost.
Considering the size of each board we realized that the SIM7600CE-T will probably exceed our width limits inside our current design of the buoy. Therefore, we decided to create 2 designs: the PCB Buoy A will contain the GSM board, and Buoy B won’t have it.