LoRaCTP: LoRa Content Transfer Protocol

The code in this repository allows to transfer blocks of bytes ("content") over a LoRa (pure LoRa, no LoRaWAN) channel. The library was tested with content of the size of up to 600kB.

It is based on a stop & wait protocol, inspired by https://github.com/arturenault/reliable-transport-protocol by Artur Upton Renault.

Folder loractp

The code in this folder is written in MicroPython and tested on:

• Pycom LoPy3 development board (discontinued)
• LoPy4 quadruple bearer MicroPython enabled development board.
• Pysense board

Firmware version: Pycom MicroPython 1.20.0.rc13 [v1.9.4-94bb382] on 2019-08-22

Files contained:

• File boot.py simply disables the WiFi to limit interferences.

• File loractp.py includes the class definition.

• File pingXXX.py and pong.py are an example of a request/response interaction. Basically, pingXXX.py sends a message and pong.py waits for a message and once received it replies it. pingrnd.py sends a random number, pingtext.py sends a text input by user.

• File plainreceiver.py shows an example of a basic receiving node.

Folder lopyserialproxy

The code in this folder offers the same functionalities of loractp.py but to be used by a generic python3 capable device (we tested it with a Raspberry Pi 3 Model B+) using the LoPy4 (connected via USB) only as a LoRa adaptor.

Remember to sudo apt install python3-serial

Code in subfolder lopy4code must be loaded in a LoPy and it starts immediately when the device is powered (ready after a 3 seconds red led blink followed by a green blink).

Code in subfolder p3code is basically the rewriting of the code in the main repository (Folder loractp).

• subfolder lsp contains:

  • file loractp.py the generic python3 version
  • file seriallopy.py the code to interface with the LoPy via serial channel.

• File ping.py can be tested with the loractp/pong.py file and is an example of a request/response interaction.

• File rndsender.py shows the example of a sender randomly sending messages in broadcast.

The ping/pong example.

To execute this example you need to have a LoPy4 (lopyA)

and a Raspberry Pi with a LoPy4 (lopyB) connected via USB

Copy files boot.py, loractp.py, and pong.py in folder loractp in the lopyA, copy all files in lopyserialproxy/lopy4code in the lopyB, and copy all files in lopyserialproxy/p3code in the Raspberry Pi.

Execute pong.py in the lopyA. The lopyB, if plugged in the Raspberry Pi should be already ready (if you have seen the 3 seconds red led blink followed by a green blink). Before executing the code in the Raspberry Pi, be sure that the serial port lopyB is connected to is '/dev/ttyACM0'. Otherwise you have to explicitely indicate it in the code when creating the CTPendpoint. Like for example:

ctpc = loractp.CTPendpoint(port='/dev/ttyACM1')

Now run in the Raspberry Pi shell:

$ python3 ping.py

You should now see a message going from the Raspberry Pi to the lopyA (ping)... and the response (pong) coming form the lopyA to the Raspberry Pi.

Caveats

1. Code based on seriallopy.py can fail to connect to the UART the first time. It is simply a matter of trying twice