ESP32 LoRa 1-CH Gateway, LoRaWAN, and the Things Network

Contributors: jimblom

Routing to The Things Network

The final components to a LoRaWAN network are a server and application. You can set up a LoRaWAN server of your own, but, for prototyping at least, The Things Network is a great, free tool for authenticating and routing your data.

If you haven't already, head to thethingsnetwork.org and create an account. Once that's done, go to your Console.

Create an Application

In order to create a device, you first need to create an application to house it under. In the console, click "Applications" then click "add application".

Fill out any ID and description you'd like. The Application EUI will automatically be generated when you create the application. You can also pick your preferred handler for the application (e.g. ttn-handler-us-west).

Create and Configure a Device

Next create a device in your application. Under the "Devices" section, click "register device".

This is again pretty simple. Fill out a unique device ID, click the "generate" button under "Device EUI" to automatically generate a EUI. Then click "Register."

This example sketch only supports ABP activation, so you'll need to modify that in the device settings. In the "Device Overview" page, click "Settings". From there, under "Activation Method" click ABP. I also recommend disabling Frame Counter Checks. The gateway is capable of frame-counter checks, but it can get out of sync -- especially if you have another gateway nearby.

Save the settings and go back to your "Device Overview" page. You should see new keys, including "Network Session Key", "App Session Key", and "Device Address." These will need to be plugged into the device sketch and uploaded to the device.

Update the Example Code

With your application, network session, and device keys in-hand, you're ready to finish configuring the ESP32 LoRa device sketch and start posting data!

On the "Device Overview" page, click the "code" symbol (<>) next to "Network Session Key" and "App Session Key" -- this will make the key visible and display it as a 16-byte array. Copy each of those keys, and paste them in place of the {PASTE KEY HERE} place-holders. "Network Session Key" should be pasted into the NWKSKEY variable and "App Session Key" should be pasted into the APPSKEY variable.

The DEVADDR variable expects a single 32-bit variable, so copy the "Device Address" key as shown and paste that into the PASTE_DEV_ADDR_HERE placeholder.

Here's an example of what your three constants should look like once done:

language:c
// LoRaWAN NwkSKey, network session key
// This is the default Semtech key, which is used by the early prototype TTN
// network.
static const PROGMEM u1_t NWKSKEY[16] = { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF, 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF };

// LoRaWAN AppSKey, application session key
// This is the default Semtech key, which is used by the early prototype TTN
// network.
static const u1_t PROGMEM APPSKEY[16] = { 0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10, 0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10 };

// LoRaWAN end-device address (DevAddr)
static const u4_t DEVADDR = 0x01234567;

And that's it! Now upload the code to your ESP32 LoRa board.

Testing the Code

After setup, the device should immediately send a "Hello, World" message. It'll continue to send a message every minute or any time the "0" button on the board is pressed.

To check if your gateway is receiving the message, you can either check the Serial Monitor or monitor the ESP Gateway Config page served by the gateway. Every time a message is received it should be added to the "Message History" table.

If messages are getting through to your gateway, click the "Data" tab on your device to check for new messages.

The message's payload -- which was encrypted between leaving the device and getting to the router -- should be a series of hex values adding up to "Hello, world".

Troubleshooting

If messages are not getting to your gateway, first make sure the channel and spread factor match up. Left unchanged, the device example code should be sending data out on the 903.9MHz channel at a spread factor of 7 (That's assuming you've set the LMIC library to CFG_us915. If it's set to a European frequency spectrum, it'll be 868.1MHz, SF7).

You can use the gateway's web server to adjust these setting on the fly. Note that the channel numbers should sequentially match the freqs array in loraModem.h -- e.g. channel 0 should be 903.9MHz (again, assuming US frequencies).

If messages are getting to your gateway, but not showing up on your TTN device console, consider changing the _TTNSERVER variable in "ESP-sc-gway.h". I haven't had success with the us-west router, but "router.eu.thethings.network" has worked perfectly (even in the US).