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This repository contains the sourcecode for a prototype called "LoRaKastl". It has been developed by 5 students at UAS Technikum Wien during the course "InnovationLab 1".

1. Introduction

The purpose of the project was to learn about LoRa/LoRaWAN and IoT programming in general. The final idea was to build a physical mailbox that notifies you on your phone, whenever it is being opened. It was meant to be a POC to overcome the inital hurdles while working with our tech stack.

1.1 Mailbox

The mailbox itself has the following components:

  • a LoRaWAN compatible microcontroller with an antenna attached to it that sends a message into the "TheThingsNetwork" once the cover is being opened, and otherwise idles in low power sleep.
  • a Reed Switch Sensor to recognize the box cover being opened
  • a battery, to power the mc
  • a 3d-printed case the mc fits in

1.2 Data Transmission

Once the data has arrived at TheThingsNetwork, it needs to be forwarded. To receive the message at our phone, we did the following:

  • TheThingsNetwork has a built in MQTT broker which we used to subscribe to our device's uplink messages via a
  • Node-RED instance - e.g. running at a remote server or a local Docker container.
  • the Node-RED instance parses the message and forwards it to the Telegram Bot API
  • in the end, the message arrives in the Telegram App.

Microcontroller -> LoRaWAN -> TTN -> NodeRed (MQTT) -> Telegram Bot

2. Prerequisites

The following things are needed in order to set up the whole message delivery pipeline:

2.1 Hardware

2.2 Software

Make sure you have

  • an Account at https://www.thethingsnetwork.org/
  • PlatformIO as VSCode extension (or any other compatible IDE)
  • Docker installed on the system your Node-RED backend should run on

3. Step-by-Step instructions

3.1 Set up the end device in your TTN account

  • Log into your TTN account
  • Create a new application and give an appropriate name
  • Register a new end device
    • Select "HelTec AutoMation" as End device brand
    • "HTCC-AB01(Class A)" as Model
    • Hardware Version "Unknown"
    • Firmware Ver "1.0"
    • Profile (Region) "EU_863_870" - the right model + image should pop up
    • Select the recommended frequency plan (SF9)
    • For the JoinEUI, enter all zeros
    • Generate a DevEUI
    • Generate an AppKey
    • Hit "Register end device"
  • leave the browser tab open

3.2 Download the repository

$ git clone https://github.com/LoRaWahnsinn/LoRaKastl.git
  • open it in VSCode via code LoRaKastl/
  • PlatformIO should recognize the configuration automatically
  • goto src/main.cpp and fill in the Variables with the values of your device registered at ttn
    • those are needed for the over-the-air-activation (OTAA)
static uint8_t devEui[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
static uint8_t appEui[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
static uint8_t appKey[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

3.3 Build & Upload CubeCell software

  • Plug your CubeCell into a USB-Port
  • Press the "Home" icon located at the bottom bar, to get to the PIO Home
  • Click left on "Devices" and check, if your device appears under the "Serial" tab
    • If its not present, (under Windows) check for optional driver updates and/or reboot your system
    • Linux users should be able to solve the problem themselves.
  • Hit "Build" (the checkmark) in the bottom bar and hope it turns out green.
  • If so, hit "Upload" right next to it.
  • As soon as the process finishes successfully, the LED on your CubeCell should begin to blink, indicating the LoRa module being active.

3.4 Test the LoRaWAN connection

  • open the PIO Serial Monitor, the socket and wait until JOINED is being printed.
  • open your ttn device browser tab and switch to "Live Data"
  • If you see a join request, the connection was successful

3.5 Test sending a message

  • attach or solder a Jumper Cable to GND and GPIO1 each
  • Bring the tho cables together and watch the Serial Monitor, it prints "SENT" if successful
  • Check the Live Data at TTN if your Message arrived (Uplink data)
  • It should contain the string "Check mail" in Hexadecimal format

3.6 Add the Reed Switch

  • connect each cable to the reed switch
  • one side has two contacts, we need the default CLOSED one
  • bring a magnet near the sensor, then release it and check, if a message has been sent
  • if a message is sent regardless of the magnet being present, try the other contact

3.7 Build & run the Node-RED docker image**

$ docker build -t lorakastl node-red/ 
$ docker run --detach -p 1880:1880 --name lorakastl lorakastl

3.8 configure MQTT

  • at TTN select left Integrations -> MQTT
  • generate a new API Key and save it, it is only viewable once.
  • note the username
  • goto http://localhost:1880
  • doubleclick the node "TTN Endpoint"
    • Hit the pencil icon to configure the MQTT server
    • Change to tab "Security" and enter your username and API Key
    • Hit Update
    • The topic you need to subscribe to has the following format: v3/<your-username-here>/devices/eui-<your-eui-here>/up - Enter your username and id of your device
    • hit Done, then hit Deploy in the upper right corner

3.9 Configure Telegram Bot

Done! Now you should (fingers crossed) get a message to your Telegram Bot, shortly after you remove the magnet from to your reed switch.