LoRa PHY driver library for the Raspberry Pi Dragino HAT

This directory provides a driver library to program LoRa devices using a Raspberry Pi 3B+ and the Dragino HAT v1.4.

Initially forked from MMw-Unibo/CLUES.

Getting started

Install Rust with a suitable linker (e.g. gcc). Install Docker and run cargo install cross --git https://github.com/cross-rs/cross to enable cross compilation. You can skip the Docker and cross setup steps if you are installing Rust on a Raspberry Pi for direct compilation.

You need a Raspberry Pi 3B and a Dragino LoRa GPS HAT v1.4 module. Install Raspberry Pi OS 64bits (tested on this version) and make sure the SPI interface is enabled with sudo raspi-config.

You can either clone this repo and install rust on the Raspberry Pis (as above, minus the installation of Docker and cross) to automatically build & run for their architecture, or you can cross compile the binaries with

cross build  --target aarch64-unknown-linux-gnu --release

and transfer them over via ssh with scp or using an USB drive. When cross-compiling, the output binaries can be found under target/aarch64-unknown-linux-gnu/release/. As an example, we provide a lora_phy binary to periodically send LoRa transmissions with various options. Transfer the binary on the first Raspberry Pi and run it with ./lora_phy. Check available options with ./lora_phy --help.

Example driver overview

The example src/main.rs driver implements the following features:

• Blocking transmission (transmit_blocking): waits for the TxDone signal on DIO0 before returning control, ensuring that a packet is fully transmitted before sending the next one
• Packet identification: each payload contains a structured header [MAGIC 0xCAFE][DEV_ID][PKT_COUNT], allowing packets to be filtered on the gateway side
• --devid option: unique device identifier (0–65535) embedded in each payload
• Jammer mode (--jammer): continuous transmission without inter-packet delay to simulate a radio jammer
• CSV logging (--log): detailed logging of each transmission with timestamp, TX duration, status, and payload in hex format
• Public sync word (0x34): packets are visible to standard LoRaWAN gateways

Architecture

code/
|-- lora/             # Rust library — SX1276 driver
|   |-- src/lib.rs    # init(), transmit_blocking()
|   ...
|-- src/              # LoRa PHY TX application (no LoRaWAN join)
|   |-- main.rs       # sending loop with CAFE header

Payload Format

Each transmitted packet contains an 8-byte header followed by random data:

Offset: 0 1 2 3 4 5 6 7 8 ...

[CA] [FE] [00] [01] [00] [00] [00] [2A] [random...]
--MAGIC-- --DEV_ID- -PKT_COUNT--padding------------

Field	Size	Description
MAGIC	2 bytes	Fixed signature 0xCAFE
DEV_ID	2 bytes	Device identifier (big-endian)
PKT_COUNT	4 bytes	Packet counter (big-endian)
Padding	variable	Random bytes up to --payload

Available Options

Option	Description	Default
--sf <7-12>	Spreading Factor	7
--freq <Hz>	Frequency in Hz	868100000
--power <2-17>	TX power in dBm	14
--payload <1-255>	Payload size in bytes	12
--wait <ms>	Delay between packets (ms)	41000
--nbpkt <n>	Number of packets to send	1000
--devid <0-65535>	Device identifier	1
--log <file>	Enable CSV logging	disabled
--jammer	Jammer mode (wait=0, infinite loop)	disabled
--down	Downchirp generation/reception	disabled
--rx	Continuous reception mode	disabled

Run examples

# Standard transmission: 100 packets, SF7, 868.1 MHz
./lora_phy --nbpkt 100

# Test with CSV logging and custom device ID
./lora_phy --sf 9 --nbpkt 500 --devid 2 --log test_sf9.csv

# Jammer mode
./lora_phy --jammer --sf 7 --power 17

Authors

Alessandro Aimi alessandro.aimi@unibo.it, Olivier Maire olivier.maire2.auditeur@lecnam.net

Copyrights

CNAM 2026