Summary

This repo provides a python library to control LoRa chips that use SPI from a raspberry Pi 5. The library supports both transmission and reception of LoRa frames. We also provide a sample file to configure a custom chip enable pin, sometime necessary for some Raspberry Pi HATs. The given example is compatible with the Dragino LoRa/GPS HAT.

The configuration of the following parameters is supported:

• Spreading factor
• Coding rate
• Center frequency
• Bandwidth
• Sync words (Network ID)
• Payload content
• Explicit or Implicit header mode
• Cyclic redundancy check (CRC)
• Transmit power
• Low data rate optimization

Installation and Usage

• Simply clone the repository
• Enable SPI on your raspberry Pi using sudo raspi-config and enabling SPI under Interface Options
• Modify the PINs connected to the reset, DIO 0 of your chip in the beginning of loralibPi5.py if needed
• Modify the SPI BUS and DEVICE you are using with your Raspiberry Pi
  • You can see wich device and bus are enables on your pi using ls /dev/spidev*. The results are \dev\spidev{BUS}.{DEVICE}
  • The default SPI BUS 0 uses GPIO 9, 10 and 11
  • Set the device based on the chip enable pin you want to use (0 for CE0 on GPIO 7, 1 for CE1 on GPIO 8) in the beginning of lo ralibPi5.
  • If you want to use a custom pin for chip enable, see the section below
• Sample receiver and transmitter codes are provided

Custom Chip Enable Pin

• The file spi-cs-extend.dts provides an overlay that can be used to create a new SPI Device with a custom chip enable pin (gpio 25 in the example).

• Compile the file to a binary using

  dtc -@ -I dts -O dtb -o spi-cs-extend.dtbo spi-cs-extend.dts

• Then place spi-cs-extend.dtbo into /boot/overlays

• Add the following line to your /boot/firmware/config.txt:

  dtoverlay=spi-cs-extend

• Reboot

• You should find that a new device /dev/spidev0.2 has been created, where 0 corresponds to the BUS and 2 to the DEVICE