What is a Bill of Materials?
Bill 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
| ITEM# | QTY | COMPONENT | TECHNICAL DESCRIPTION | OTHER INFORMATION |
|---|---|---|---|---|
| #1 | 1 | Arduino Mega R3 | ATmega2560 256 KB of Flash Memory, 8 KB of SRAM, and 4kB of EEPROM Clock Speed: 16 MHz | Units purchased in Aliexpress and other cheap stores are generally reliable and cheaper than official ones. 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. |
| #2 | 1 | DC Motor driver | Bi-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) |
| #3 | 1 | Linear actuator | 12v 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. |
| DEPRECATED | BNO055 IMU has low reliability due to its hardcoded uncontrollable automatic calibration. Integration of this IMU has been discontinued in Fenix. | |||
| #4a | 1 | IMU ICM-20948 | ICM-20948 is considered the upgrade for the popular (and now discontinued) MPU-9250. The chip integrates 3-axis gyro and 3-axis accelerometer and 3-axis magnetometer. 2 breakout alternatives from SparkFun or Adafruit: SparkFun 9DoF IMU Breakout – ICM-20948 (Qwiic) Adafruit TDK InvenSense ICM-20948 9-DoF IMU | Only SparkFun 9DoF IMU Breakout has been tested. |
| #4b | 1 | IMU LSM6DS33&LIS3MDL | inertial measurement unit (IMU) that packs an LSM6DS33 3-axis gyro and 3-axis accelerometer and an LIS3MDL 3-axis magnetometer. 2 breakout alternatives from Pololu and Adafruit: MinIMU-9 v5 Adafruit LSM6DS33 + LIS3MDL | Only the Pololu MinIMU–9 v5 has been tested. |
| #5 | 1 | Bluetooth module | HC-05 | Ensure you purchase HC-05 and not HC-06. |
| #6 | 1 | Step-down converter | DC-DC Step-down converter, M2596, 1,25 V-30V | Use the screwed potenciometer to regulate the output to a voltage between 8.5V and 12V. Recommended: 9V. |
| #7 | 1 | Fenix Shield | As 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 Bill of Materials
| ITEM# | QTY | COMPONENT | TECHNICAL DESCRIPTION | OTHER INFORMATION |
|---|---|---|---|---|
| #1 | 8 | Arduino stacking headers | Extra 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. |
| #2 | 1 | 2 pin screw terminals | 0.2″/ 5.08mm pitch. 0.9 pin width | |
| #3 | 1 | 3 pin screw terminals | 0.2″/5.08mm pitch. 0.9 pin width | |
| #4 | 1 | Buzzer | Voltage: 5v Diameter: 12mm; Pitch: 6,5mm; | Alternative installation: wired buzzer far from the PCB |
| #5 | 1 | Resistor | 1 Kohm | |
| #6 | 1 | Resistor | 2.2 Kohm | |
| #7 | 1 | STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable – 150mm Long | 4 pins | PCB is designed to fit directly all components. However it is recommended to install electronic compass 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. |