Build of Materials

What is a Build of Materials?

Build of Materials (aka. BoM) is the list of components that build up a complete Fenix Autopilot system.

Identify materials and purchase

First step is to identify which are the components required.

Then search those on the Internet to have a better view on what are we talking about. Ensure you understand the technical description to avoid purchasing wrong components.

Purchase the components. All components are standards you can find on the Internet or in the most convenient electronic shop in your city.

I give different examples of shops on the Internet where the product is available but you have many other alternatives.

Fenix Autopilot BoM

#11Arduino Mega R3ATmega2560
256 KB of Flash Memory, 8 KB of SRAM, and 4kB of EEPROM
Clock Speed: 16 MHz
Also USB A/B Cable (typical for printers) is needed to connect to laptop. Usually you have an old one at home or you can puchase it together with the Arduino.
#21DC Motor driverBi-directional control for 1 brushed DC motor
Support motor voltage ranges from 7V to 30V
Maximum current up to 10A continuous and 15A peak
Arduino compatible shield (recomended)
You can select different DC Motor drivers, but the recommended one is Cytron 10A DC Motor Driver Arduino Shield which has been tested in this project.

Cytron requires to set the jumpers to the right PINS (D6 and D7)
#31Linear actuator12v
Stroke: 300mm with potenciometer
Recommened minimum power/speed ratio: 300N 27mm/s
Very important, remember to select a linear actuator with potenciometer. These have 5 wires instead of 2.
#4a1IMU CJMCU-055CJMCU-055 contains BNO055 IMUCJMCU-055 from Aliexpress and other cheap retailers tested and documented as part of this project.
Other integrations of BNO055, like the Adafruit one might require changes in the code or the wiring diagrams and are not recommended
#4b1IMU MinIMU9v5IMU MinIMU9v5 packs LSM6DS33 3-axis gyro and 3-axis accelerometer and an LIS3MDL 3-axis magnetometer.The Pololu MinIMU9 v5 is an inertial measurement unit (IMU) that packs an LSM6DS33 3-axis gyro and 3-axis accelerometer and an LIS3MDL 3-axis magnetometer.
#51Bluetooth moduleHC-05Ensure you purchase HC-05 and not HC-06.
#61Step-down converterDC-DC Step-down converter, M2596, 1,25 V-30VUse the screwed potenciometer to regulate the output to a voltage between 8.5V and 12V. Recommended: 9V.
#71Fenix ShieldAs described below
  • Only one (1) IMU device shall be installed: #4a or #4b. You can choose based on availability and price in your country.
  • Arduino will be powered by 12V battery using a step-down converter with 9V output (between 8.5V and 12V is acceptable). Less tension will force Arduino to take power source from USB leading Arduino to reset if current is too low (this happens with Raspberry Pi USB).
  • Breaker at the +12V entry should be used for security (Max. 10A recommended).

Fenix Shield

What is Fenix Shield?

This is a bespoke Arduino Mega Shield designed for Fenix Autopilot. This is an assembly which is further described in Fenix Shield BoM below.

It is composed of a PCB and some electronic components attached to it.

Fenix PCB

You can order the PCB in you local electronics shop or in any Internet supplier. One of the most known is JLCPCB.

PCB As-Build diagrams are available to be downloaded in the link below.

Check here the last release. of PCB As-Build

Shield Build of Materials

#18Arduino stacking headersExtra large pins.
8 pins each.
0.1″/ 2.54mm pitch
A row of 16 pins of Break Away Headers can be used instead of 2x 8 pins Stacking headers.
Remove 2 pins from one stackng header to fit the 6 holes line.
#212 pin screw terminals0.2″/ 5.08mm pitch. 0.9 pin width
#313 pin screw terminals0.2″/5.08mm pitch. 0.9 pin width
#41BuzzerVoltage: 5v
Diameter: 12mm;
Pitch: 6,5mm;
Alternative installation: wired buzzer far from the PCB
#51Resistor1 Kohm
#61Resistor2.2 Kohm
#71Connector5 pins
Pitch: 2.54mm
Wire: 24AWG
PCB is designed to fit directly all components. However it is recommended to install electronic compass (BNO055 IMU) far from the buzzer to avoid EMI and installed with x-axis aligned to the hull of the boat. Reason why alternative use of wired connectors to IMU is recommended. For other components, optional.

Notes on IMU BNO055

  • Shortcircuit S0 and S1 negative poles (solder zones in the picture below keeping + pole isolated.)
  • Install crystal oscilator delivered with the IMU into the available places.