Buoy A | Hackaday Dream Team 2020

Buoy A V1.0 is a 141.73 mm x 54.86 mm PCB that integrates the 5 main components (ESP32, LoRa, GPS, Motor Driver and GSM/GPRS).

Main Components

Main components of Buoy A v1.0.

Sources:

• ESP32: ESP32-DEVKITC-32D
• LoRa: RFM95W LoRa Radio
• GPS: Adafruit Ultimate GPS
• Motor Driver: TB6612FNG MOTOR DRIVER BOARD
• 4G(LTE): SIM7600CE-T 4G(LTE) Arduino Shield

Schematic

Schematic of Buoy A v1.0.

For more information about the design check the original post in the project's page.

Layout

PCB Layout of Buoy A v1.0.

PCB

PCB: Front Layer.

Assembly

Components of Buoy A v1.0.

Components List:

1. ESP32-DEVKITC-32D
2. TB6612FNG MOTOR DRIVER BOARD
3. CONN HDR 5POS 0.1 GOLD PCB
4. CONN HEADER VERT 3POS 2.54MM
5. CONN HDR 6POS 0.1 TIN PCB
6. CONN HDR 8POS 0.1 TIN PCB
7. CONN HDR 8POS 0.1 TIN PCB
8. CONN HDR 8POS 0.1 TIN PCB
9. CONN HDR 19POS 0.1 TIN PCB
10. CONN HDR 19POS 0.1 TIN PCB
11. PCB Buoy A V1.0
12. CONN HEADER R/A 3POS 2.5MM
13. TERM BLK 3P SIDE ENT 5.08MM PCB
14. TERM BLK 2P SIDE ENT 5.08MM PCB
15. CONN HDR 9POS 0.1 GOLD PCB
16. CONN HDR 9POS 0.1 GOLD PCB
17. 2 CONN HDR 2POS 0.1 GOLD PCB
18. CONN HDR 9POS 0.1 GOLD PCB
19. CONN HDR 10POS 0.1 TIN PCB
20. CONN HEADER VERT 3POS 2.54MM
21. Adafruit Ultimate GPS
22. RFM95W LoRa Radio
23. SIM7600CE-T 4G(LTE) Arduino Shield

For a detailed Bill of Materials visit the following post.

For a detailed explanation about the soldering and assembly procedure visit the following post.

Wiring Diagrams

The following diagrams present the physical connections of the different boards and components of the Buoy A V1.0:

Power Management

• Battery (5V < Voltage < 15V)
• PCB Board Buoy A V1.0
• Buck Converter
• Switch
• Extra capacitor

Wiring diagram: Power Management with Buck Converter.

Similar to Buoy B, there is an alternative for the battery management, is possible to provide the required voltages with a boost converter and a 3.7V Battery, like the following example:

• 3.7V 1 Cell Battery
• PCB Board Buoy A V1.0
• Boost Converter
• Micro USB Breakout Board
• Switch
• Extra capacitor
• JST-XH 2 Pos female connector and a JST-XH 2 Pos male connector
• 5V Charger (only used to charge the battery)

Wiring diagram: Power Management with Boost Converter.

This alternative is valid and possible, but is not ideal for longer working time (compared to the first one). It is important to consider the efficiency of the boost converter. The selected boost converter will have a voltage drop at a current higher than 500mA, that should be taken into consideration.

Motors

The board was designed to handle 2 different types of motors, those are:

• Servo Motor

Wiring diagram: Buoy A v1.0 with Servo Motor.

• DC Motor (using the driver TB6612FNG)

Wiring diagram: Buoy A v1.0 with DC Motor.

For more information about the wiring diagrams and the project visit the following post.

  Firmware

Buoy A and Buoy B run the same ESP32 firmware — a captive Wi‑Fi access point with a DNS‑resolved web UI served from SPIFFS, TinyGPSPlus for the GPS, a 915 MHz RFM95W LoRa link to the topside Onboard Gateway, and the release‑timer countdown. Buoy A differs only in which parts are populated: it also carries the TB6612FNG motor driver and an optional SIM7600 GSM/GPRS shield for a cellular uplink where there is coverage.

The Buoy A firmware repository holds the library requirements; the buildable sketch is in the Buoy B firmware repository.

Future Improvements

For more information about the recommended future improvements for the electronic design visit the following post.