Building a prototype to send GPS location data to the Helium (Lora) network

This project provides step-by-step instructions for building a prototype device that sends GPS location data to the Helium (Lora) network. The prototype utilises an ESP32 development board, a Lora RFM95W 915MHZ (SX1276) module, and a GPS module (GY-GPS6MV2). The instructions cover connecting the Lora and GPS modules to the ESP32 board, adding the device to the Helium network, and setting up a test/debug environment using pipedream.com. The file also includes images to assist in the building process.

The GPS/Helium test drive though Singapore

Helium GPS prototype	Connection test drive

Test drive successful transmits	Helium hotspot map(explorer.helium.com)

How to use the code

Components

• Lora RFM95W 915MHZ (SX1276) - Make sure you have the correct board with frequency you need!
• ESP32 development board
• GPS module (GY - GPS6MV2)

Connect the lora module

Connect the GPS module

Add you device to the Helium network

Go to the Helium console (console.helium.com/devices) and add a new device (see below). You will need later the “Device EUI”, “App EUI” and “App Key”.

Add a new device	Pending device creation

Set up your test/debug environment (Optional)

I used pipedream.com to receive, temporary store and retrieve the packages I sent it the Helium network. You can sign up (pipedream.com/auth/signup) and get the payload of you your packages (see below).

You will also need to add a new integration (console.helium.com/integrations/new) in the Helium console to add the pipedream endpoint as receiver of your messages. Furthermore you need to create a flow in the Helium console (console.helium.com/flows) which then instruct the Helium console to send the packages to pipedream (see below).

Helium console flow (console.helium.com/flows)	pipedream.com

Setting up the Arduino environment

• 1. Install "MCCI Arduino LoRaWAN LMIC library" (https://github.com/mcci-catena/arduino-lorawan/)
  • 1.1 Go to Sketch > Include Library > Manage Libraries.
  • 1.2 In the search bar, type in the name of the library you wish to install and click on the library in the search results.
  • 1.3 Click on the "Install" button to install the library.
• 2. Change the "lmic_project_config.h" file
  • 2.1 Go to "/libraries/MCCI_LoRaWAN_LMIC_library/project_config/lmic_project_config.h"
  • 2.2 Add the lines below and comment or remove everything else

<li>3. Add your "Device EUI", "App EUI" and "App Key" to the "helium_crd.h" file.
<ul>
<li>2.1 "Device EUI" needs to be added as LSB (Little-endian). </li>
<li>2.2 "App EUI" also needs to be added as LSB.</li>
<li>2.3 But "App Key" needs to be added as MSB.</li>
</ul>

“lmic_project_config.h” file

#define CFG_as923 1
#define CFG_sx1276_radio 1
#define LMIC_LORAWAN_SPEC_VERSION LMIC_LORAWAN_SPEC_VERSION_1_0_3

Configuration are meant to be used for the Singapore/AS923 frequency.

“helium_crd.h” file. Example: APPEUI from the Helium console “123456890abcdef”

static const u1_t PROGMEM APPEUI[8] = { 0xEF,0xCD,0xAB,0x90,0x78,0x56,0x34,0x12};

What if it does not work?

• Make to have the correct module with the right frequency!
• Make sure you added “Device EUI”, “App EUI” and “App Key” in the right order and you do not have any mistakes in it.
• Make sure you are close to (ideally to several) Helium hotspots (explorer.helium.com).
• Check your cabling!
• Helium/Lora is very time sensitive protocol (based on the internet) make sure you do not delay or block the “os_runloop_once()” function for too long. The function needs to be called constantly my experience.
• Your code does not compile right at the beginning after installing the library? Make sure to close and reopen the Arduino IDE.
• Always get “no JoinAccept”? Can mean many things: No hotspot close by, wrong “Device EUI”, “App EUI” or “App Key, cable issue, …

What to do next?

• Improve the software and some timing issues.
• Add more debug messages to understand issues better.
• Build a prototype which can be used for an extended time e.g. temperature sensor in a remote area.
• How can we use Software Defined Radio (see below) to better analyse and understand the protocol and issues with a prototype.