LoRa and The Things Network

Configure the Dragino LoRa/GPS Hat for the Raspberry Pi 3 to use the Raspberry as LoRa Gateway (with connection to The Things Network) and as LoRa Device (sender).

Software

The following software was used:

• LoRa Gateway: https://github.com/tftelkamp/single_chan_pkt_fwd
• LoRa Device: https://github.com/ernstdevreede/lmic_pi

Configure the Raspberry as LoRa TTN Gateway

Preperation

• Use the raspi-config tool (with sudo raspi-config) to enable SPI on the Raspberry Pi
• Install wiringpi (sudo apt-get install wiringpi)

Download

• Download and unzip the software for a Single Channel Gateway:
  wget https://github.com/tftelkamp/single_chan_pkt_fwd/archive/master.zip
unzip master.zip

Configuration

• The server address which is used by the gateway software must be changed to one of the TheThingsNetwork servers

• Use the nearest TTN server (e.g. 'eu.thethings.network'). The IP address can be resolved using the nslookup command.

• Edit the main.cpp file and insert the IP address of the server 'eu.thethings.network' (in line 88, into the define SERVER1):
  #define SERVER1 "52.169.76.255"

• The full source code can be found in lora_ttn_gw/.

Build and Run

• Build the program by calling make
• Execute the compiled program: ./single_chan_pkt_fwd
• The output of the program contains a Gateway ID. This ID is needed to register the gateway on the The Things Network website.
• The script ./start_lora_ttn_gw.sh starts the gateway program and restarts it if it should crash.

Autostart LoRa TTN Gateway

The LoRa TTN gateway program can be set up to automatically start on boot.

• Edit the file /etc/rc.local: sudo vi /etc/rc.local
• Add the following line (before exit 0):
  /path/to/lora_ttn_gw/start_lora_ttn_gw.sh &
  notice the & at the end!

Configure The Things Network

Create the Gateway

Use the Gateway ID printed by the gateway program to create a new gateway on the TTN website. Because the gateway software is older, it is important to tick I'm using the legacy packet forwarder.

• Insert the gateway ID without the ':'
• Tick the 'I'm using the legacy packet forwarder' checkbox
• Enter a description
• Select the frequency plan (europe)
• Select a router (europe, the one that was configured in the gateway software)

The image below shows the Register Gateway screen:

Configure a New Device in TTN

• Create a new Application on The Things Network (and open it)
• Register a new device inside the application
• Important: Use the Activation Method ABP
• After creating the device, the device details page contains the required IDs and keys
• The Device Address, Network Session Key and App Session Key are used in the next step

The screenshot below shows the newly created device and the device parameters (IDs and Keys):

Configure the Payload Format in TTN

The full decoder source code can be found in ttn_setup/payload_decoder.txt.

Configure the Raspberry as LoRa TTN Device (sender)

Preperation And Download

• Enable SPI and install the wiringpi package on the Raspberry (as described in the gateway description above)
• Download and unzip the software for a LoRa End Device:
  wget wget https://github.com/ernstdevreede/lmic_pi/archive/master.zip
unzip master.zip

Configuration

Edit the thethingsnetwork-send-v1.cpp file and replace the Device Address, Network Session Key and App Session Key in DEVADDR, DEVKEY and ARTKEY respectivly.

Important: the keys must be in MSB order!

Modifications to the source code

• The thethingsnetwork-send-v1 example code was used as base
• The code was modified to allow sending of one 'data item' from a python script
• The details are described in the lora_ttn_sender/readme.md.

The full source code can be found in lora_ttn_sender/.

Build and Run

• Build the program by calling make
• Use the bash script to start the lora ttn sender: ./send_to_ttn.sh <data>
  the string is sent to the The Things Network.