LoRaWAN Firmware for autonomous ships. This code consists of two major parts, a feather M0, RFM95 LoRaWAN located on a base station, and one located on the ship. The pin definitions of the feather boards are shown below.
The Base Station sends a packet over LoRaWAN that currently only contains one letter corresponding to an operation Mode. The letters are interpreted by the boat as follows:
| Letter | Mode | Color |
|---|---|---|
| A | Autonomous | G |
| S | Secondary | G |
| M | Manual | Y |
| E | Emergency Stop | R |
Pin D12 is used to check if the E-Stop button has been pressed. If the pin is set low (False) which it is by default, the E-Stop status is interpreted as False. If pin D12 is pulled high (True) the E-Stop condition is set to true, and an E-Stop packet is immediately sent to the boat. It is reccomended to connect D12 to a normally opened button that when closed, connects D12 to the USB pin.
The Feather M0 onboard the ship is flashed with everything in the boat directory. This directory will eventually have it's own readme consisting of the below sections and their elaborations.
Two control pins controll a red, green, and yellow light to show what mode of operation the ship is in. Digital Pins D11 and D12 are used for this as follows:
| OPM1 (D11) | OPM2 (D12) | Color |
|---|---|---|
| 0 | 0 | R |
| 1 | 0 | Y |
| 1 | 1 | G |
The ship reports back to the base station a byte array across LoRa which can be modeled as a Binary Symmertic Channel (BSC). The byte array can be decoded as a UTF-8 sentence consisting of densely packed data. The data can be interpreted as follows:
| OpMode | Link | E-Stop | GPS | Jetson Link | Jetson Data | /n | |
|---|---|---|---|---|---|---|---|
| Size (bytes) | 1 | 1 | 1 | 20 | 1 | X | 1 |
| Byte Location | 0 | 1 | 2 | 3-24 | 25 | 26-98 | 99-100 |
| Values | A,S,M,E | L,N | T,F | 123.45,,... | J,K | X | \n |
| Purpose | Main Operation Mode | Link To Base | Manual Button | GPS@10Hz | TF Link to Jet. | Anything Sent From Jet. | EOL/EOF |
An example message reads: ENF123.45,,12.34,,123.45...JSTANDBY... and prints a new line to the terminal. This data is interpreted from left to right meaning:
E: E-Stop Mode is active.
N: The reason for this is there is no link to the base station.
F: The condition of the manual E-Stop button on board is False.
123.45,,...: The GPS coordinates updated every 10 seconds.
J: There is an active link to the Jetson.
STANDBY: The message 'STANDBY' was recieved from the Jetson.
/n: Newline. This is the end of the message.