Mesh-Lora

This repository was developed for my bachelor-thesis at the technical University of Vienna as part of a project for the firebrigard in lower austria.

Based on the adafruit_rfm9x library it allows to send messages over the adafruit rfm9x module. compared to the native library however, a greater address range as well as larger messages are possible (sent as multiple packages).

How to run

Module connection

The first step is to connect the raspberry pi to the module, as shown below.

Pi	rfm9x
3.3V	VIN
GND	GND
GPIO 5	G0
GPIO 25	RST
SCK	CLK
MISO	MISO
MOSI	MOSI
CE1	CS

Setting options

Per default the repository should contain a config.yaml file. Here the options for the program can be set.

The options specified there are (The default can be seen below):

• uuid_file: path to a file containing the id of the node. e.g. 2b679c67277302db4ca0ae3fcbad51d3
• message_folder: path to a folder for storing and reading messages. Received messages will be stored here. File created according to the naming convention will be read and sent.
• message:
  • ms_memorize_received_message_id: time to memorize that a message was received already-
  • broadcast_address: address that will be recognized as broadcast address.
  • meta:
    • length_id: length of the node id in bytes.
    • length_pid: length of the pid for addressing messages in bytes.
    • length_frame: total length of message in bytes.
    • length_message_id: length of the message id in bytes.
    • length_sequence_number: length of the sequence number for messages in bytes.

uuid_file: 
message_folder: "./storage/" # "~/tmp/lora"
message:
  ms_memorize_received_message_id: 50000
  broadcast_address: "00000000000000000000000000000000"
  meta:
    length_id: "16"
    length_pid: "2"
    length_frame: "124"  # "100" # 252
    length_message_id: "1"
    length_sequence_number: "4"  # expected to be even length

Running

To run the project it first has to be downloaded from github using git clone.

After installing the requirements (pip3 install requirements.txt), the program can then be run using python3 ./src/main.py ./src/config.yaml

To send messages a file has to be created in the folder specified by the message_folder option. The name of the file should be of the form: OUT_[SENDER-PID]_[RECIPIENT]_[RECIPIENT-PID].

• OUT: Marks files that should be transmitted
• [SENDER-PID]: The process id of the process sending the message.
• [RECIPIENT]: The address of the recipient.
• [RECIPIENT-PID]: The pid of the process that should be addressed.

The file content then corresponds with the messages content.

Upon receiving a message, a file is created following the pattern IN_[PID]_[SENDER]_[SENDER-PID]_[Message-id].

• IN: marks the message as received. A process utilizing this project can scan the folder for messages starting with IN to check for incoming messages.
• [PID]: The process id of the recipient process.
• [SENDER]: The adress of the sender. Can be used to send responses.
• [SENDER-PID: The pid of the sender. Also to be used for responses
• [Message-id]: To guarantee uniqueness of filenames.