LoRaWAN The Things Network


#1

Has anybody looked at connecting to The Things Network, TTN, via LoRaWAN. There is a RFM9x library available for 915MHz LoRa modules, but connection to the LoRaWAN TTN gateways is needed.

We are looking to use the IMP004m modules for high-altitude ballooning, where they will be out of range of WiFi, but can transmit limited data via LoRa during flight.


#2

RFM9x don’t do LoRAWAN, they do LoRA. LoRAWAN is another protocol stack on top of LoRA, which is not implemented in the HopeRF chips; the actual LoRAWAN gateways are specialized radios with multiple receivers running concurrently.

For LoRAWAN nodes there are other options, like the Microchip modules, see https://developer.electricimp.com/libraries/hardware/rn2xxx

Note that the library there uses the RN2xxx in LoRA (not LoRAWAN) mode, but you could pretty easily make the driver work in LoRAWAN mode.


#3

Thanks for the feedback Hugo. Please bear with me as I try to sort through the technology. I tested the SparkFun LoRa Gateway - 1-Channel (ESP32) https://www.sparkfun.com/products/15006, and was able to connect to The Things Network. It uses the RFM95W module. I picked up an RFM95W module from Adafruit https://www.adafruit.com/product/3072, and figured I could do the same thing with the IMP004m, perhaps using the RFM9x library https://github.com/electricimp/RFM9x/tree/develp. I think your point is that there is an additional protocol stack on top of the basic LoRa communication.

Moving to LoRa gives us a huge power savings, and if we can use LoRaWAN, we can leverage off of other gateways and The Things Network for more robust tracking. Here’s a story about balloon tracking with LoRaWAN: https://www.thethingsnetwork.org/labs/story/tracking-a-stratospheric-balloon-with-iot.

Do you still advise looking at the Microchip modules or can we work with the RFM95W? Perhaps there are other options.


#4

Ah, yes, there the LoRAWAN stack will be running on the ESP32 (dumb radio, stack on “host”); the Microchip modules I linked have the stack on the radio chip.

Technically, if there was a stack on squirrel you could do the same with an imp, but there isn’t one; it may be possible to port one (the C code used in the Sparkfun demos is https://github.com/mcci-catena/arduino-lmic/tree/master/src/lmic ), but assuming you’re not making thousands of balloons, it may just be much easier to use the Microchip module - or any other module with the stack integrated.

eg see the ones here: https://www.loriot.io/modems.html


#5

As always Hugo, your comments are very helpful. I think I’ll leave porting the lmic code to Squirrel to someone else.

The loriot.io list is a great overview of the LoRa modem technology. The Microchip module looks like a nice way to go.