The path to LoRaWAN

In 2017 I already tried to get a LoRa based radio link working. Which worked, but only as a
local send / receive solution. At the time The Things Network (TTN) was already operational, but it was quite complex to get started with it, certainly if you don't live near a public TTN node so you could not just send some data to it. I briefly considered setting up my own station, but at an estimated cost of €300,- this was still a bit too much for just a hobby project.

Nowadays TTN has matured, and it is easier to find information on how to access it. There is a complete description on Adafruit on how to build a single channel gateway, and there are several DIY project on how to build simple LoRa Nodes. 
The easiest way would of course be to buy a complete LoRa enabled board, like the LoPy,  the Adafruit Feather with LoRa,  the WISEN Whisper Node, the MIKRO Electronika Lora5 Click, or just one of the TTN products. (And there are many more, just Google 'LoRa Board')
 
But I already have these Dragino LoRa Bee units and I want to use them. Should not be that hard since they are basically just RF95W transceiver modules on a carrier board. And the RF95 modules are at the heart of 99% of all other LoRa devices. 
A very nice description of a DIY LoRa node is described by Mario Zwiers in a few blog posts that basically describe what I wanted to do. He created a small PCB with an Arduino Micro, a battery charger and a bare RF95W module. Unfortunately he just created the PCB from scratch, without a schematic. So I have to figure that out myself, but since the combinations are limited that cannot be too hard.

Connecting LoRa Bee and Raspberry Pi Zero W

 Pi to LoRa Bee wiring:

• 3.3V to Raspberry Pi 3.3V
• GND to Raspberry Pi Ground
• DIO0 to Raspberry Pi GPIO #3
• RST to Raspberry Pi GPIO #25
• SCK to Raspberry Pi SCK
• MISO to Raspberry Pi MISO
• MOSI to Raspberry Pi MOSI
• CS to Raspberry Pi CE1  

Next I followed the basic instructions on installing Python. First installed the latest Raspbian to an SD card. Booted it on the Pi, and used raspi-config to set a Hostname, new password, and the WiFi network parameters. And from the 'Interfacing Options' section I also enabled SSH, SPI and I2C.

Run the standard updates:
sudo apt-get update
sudo apt-get upgrade
and
sudo pip3 install --upgrade setuptools
If above doesn't work try
sudo apt-get install python3-pip

Then install the GPIO libraries:
pip3 install RPI.GPIO

And the Adafruit libraries:
pip3 install adafruit-blinka 

(All this is also on the Adafruit site, I just repeated the steps here for convenience)

Next install the RFM libraries:

sudo pip3 install adafruit-circuitpython-rfm9x

After that I created a simplified version of the Adafruit sample program that would just check if the RFM unit was connected and working. Note that I changed the frequency setting in the RFM9x() function to 868.0, which is the frequency used in Europe.



#Learn Guide: https://learn.adafruit.com/lora-and-lorawan-for-raspberry-pi
#Author: Brent Rubell for Adafruit Industries

import time
import busio
from digitalio import DigitalInOut, Direction, Pull
import board

# Import the RFM9x radio module.
import adafruit_rfm9x


# Configure RFM9x LoRa Radio
CS = DigitalInOut(board.CE1)
RESET = DigitalInOut(board.D25)
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)

    # Attempt to set up the RFM9x Module
try:
    rfm9x = adafruit_rfm9x.RFM9x(spi, CS, RESET, 868.0)
    print("RFM9x: Detected")
except RuntimeError:
    # Thrown on version mismatch
    print("RFM9x: ERROR")

time.sleep(0.1)

And it works:

 

The instructions tell you to clone the GIT repository . But GIT is not installed by default on  Raspbian. Use the following commands to get it :

$ sudo apt-get update
$ sudo apt-get install git-core

Next step would be to install WiringPi. But there is a slight problem: WiringPi is no longer available at the URL as given in the instructions. Apparently the creator of this library has given up on the open source community. Fortunately there is still a mirror of the code at Github, which then probably is no longer maintained but will work fine with most projects.:

git clone https://github.com/WiringPi/WiringPi

Build it using 'sudo ./build'

Installing and running the Single Channel Gateway

The proceed to the next step, getting the single channel gateway code:

git clone https://github.com/adafruit/single_chan_pkt_fwd.git

This can now be built by using 'sudo make all'

Since I wired the RPi directly to my Lora Bee, and did not add any buttons or the display I had to modify the code in 'lorawan_gateway.py' so there were no references to the display any more and everything was just printed to the console. My modified code:

 
Now, what is not mentioned in the Adafruit guide is the fact that the unit is set-up according the settings in the file 'global_conf.json'. Which I had to modify to get it going for Europe.  I changed the frequency to 868.1 Mhz, and I swapped the servers so the router.eu is now the first in the list. Also set this to 'enabled:true', and the router.us to false. and changed the "is_pi_xero":true (since I am using a Pi ZeroW for my gateway). Also note that "pin_dio0" is set to 3. So it should be connected to GPIO 3, and not (as written on the AdaFruit page) to 5.

{
  "SX127x_conf": {
    "freq": 868100000,
    "spread_factor": 7,
    "pin_nss": 11,
    "pin_dio0": 3,
    "pin_rst": 25
  },
  "gateway_conf": {
    "ref_latitude": 0.0,
    "ref_longitude": 0.0,
    "ref_altitude": 10,
    "name": "Reigersbek51",
    "email": "me@email.com",
    "desc": "RPi Zero-LoraBee 1-Ch Gateway",
    "is_pi_zero": true,
    "servers": [
      {
        "address": "router.eu.thethings.network",
        "port": 1700,
        "enabled": true
      },
      {
        "address": "router.us.thethings.network",
        "port": 1700,
        "enabled": false
      }
    ]
  }
}
 
Now I can start the gateway.: python3 lorawan_gateway.py
and register the gateway at The Things Network.

Full description is on this page, no need to repeat it here...

But after completing the registration and starting the gateway it did not work. It did not show 'connected'. Then I noticed that when the gateway is started it prints  the Gateway ID. And that was all 00:00:FF:FF:00:00. So it looks like though the Python program displays the correct ID, the gateway code itself does not. Checking the code I noticed that there is a special case made for the Raspberry Pi Zero, which I am using. And in the initialisation I also see that 'Pi Zero' is set to 0. Even though I have changed this in the global_config.json to 'true' The fastest fix was to change line 102 in the .cpp file to: 

bool is_pizero = true;

My Modified code on GIST is here.

and run another 'sudo make all' .Which solved the problem.

The Sandbox Single Channel Gateway (LoRa GO DOCK)

The setup with the Raspberry Pi W and the LoRa Bee works fine. But just after finishing this,

I discovered the LoRa GO DOCK. At only $19,- this is a super cheap gateway, based on the ESP8266 so it's programmable using the Arduino IDE. Once programmed and configured the operation is similar to the RPi version, so it is a much easier solution. It's also super small, and comes with two antennas. The only drawback is that it has to come from China so it takes two to three weeks to deliver.