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NB: This is no longer developed

LoRaWAN

This is a LoRaWAN v1.0 implementation in python for the Dragino LoRa/GPS HAT, it is currently being used to connect to the things network https://thethingsnetwork.org. It is based on work at https://github.com/jeroennijhof/LoRaWAN

It uses https://github.com/mayeranalytics/pySX127x.

See: https://www.lora-alliance.org/portals/0/specs/LoRaWAN%20Specification%201R0.pdf

Hardware Needed

  • Raspberry Pi
  • SD card
  • LoRa/GPS HAT
  • Raspberry Pi power supply

Installation

  1. Install Raspbian on the Raspberry Pi
  2. Enable SPI using raspi-config
  3. Enable Serial using raspi-config (no login shell)
    1. check your serial ports 'ls /dev/serial*'
    2. check the serial port is receiving GPS data with 'cat /dev/serialx' where x is your port number.
  4. Install the required packages sudo apt install device-tree-compiler git python3-crypto python3-nmea2 python3-rpi.gpio python3-serial python3-spidev python3-configobj
  5. Download the git repo git clone https://github.com/computenodes/LoRaWAN.git
    1. make a copy of dragingo.ini.default cp dragino.ini.default dragino.ini
    2. make sure your dragino.ini is set to use the serial port from step 3
  6. Enable additional CS lines (See section below for explanation)
    1. Change into the overlay directory cd dragino/overlay
    2. Compile the overlay dtc -@ -I dts -O dtb -o spi-gpio-cs.dtbo spi-gpio-cs-overlay.dts. This might generate a couple of warnings, but seems to work ok
    3. Copy the output file to the required folder sudo cp spi-gpio-cs.dtbo /boot/overlays/
    4. Enable the overlay at next reboot echo "dtoverlay=spi-gpio-cs" | sudo tee -a /boot/config.txt
    5. Reboot the Pi sudo reboot
    6. Check that the new cs lines are enabled ls /dev/spidev0.* should output /dev/spidev0.0 /dev/spidev0.1 /dev/spidev0.2. In which case the required SPI CS line now exists
  7. Create a new device in The Things Network console and copy the details into the config file dragino.ini
  8. Run the test programm ./test.py and the device should transmit on the things network using OTAA authentication
  9. run './test_downlink.py' to check downlink messages are received (after scheduling one in the TTN console)

Additional Chip Select Details

For some reason the Dragino board does not use one of the standard chip select lines for the SPI communication. This can be overcome by using a device tree overlay to configure addtional SPI CS lines. I am not a device tree expert so I adapted the example given at https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=157994 to provide the code needed for this to work.

Downlink messages

See https://www.thethingsnetwork.org/docs/lorawan/classes/ for a complete description of LoRaWAN device classes.

Briefly, for class A device, downlink messages will only be sent after an uplink message. This is generally the type of device most people will be using as it consumes the least power on, for example, Arduino sensor devices. However, a Raspberry Pi + dragino HAT is constantly powered so when it isn't transmitting it can be always listening.

TODO

  • Make code more readable and easier to use (From upstream)
  • investigate device tree compilation warnings