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TTN/LoRa using Dorji DRF1272F module

Communicating over #LoRa The Things Network using Dorji DRF1278F module  @oostenvr  #IoT

  • The module has 13 contacts, but not all are required for the LMIC Arduino library .
  • The Dorji modules are currently among the cheapest LoRa modules available on Ebay .
  • So some weeks ago I ordered a DRF1272F 868MHz module for about $8, which arrived this week.
  • Franz, one of the members of the TTN Nijmegen community , started experimenting with node-to-node communication using Dorji DRF1278F 433MHz modules.
  • On the software side I am using Arduino 1.6.9, the LMIC library and the same sketch that I have been using with the RFM95W module.

Sofar I have been experimenting with LoRa and TTN using a Multitech MDot board and with a HopeRF RFM95W module connected to a Teensy, but I decided to try something else. Franz, one of the members of the TTN Nijmegen community, started experimenting with node-to-node communication using Dorji DRF1278F 433MHz modules. I’d like to support him in converting to 868MHz, so that he can post data to TTN once a gateway become available in his range.

@thethingsntwrk: Communicating over #LoRa The Things Network using Dorji DRF1278F module @oostenvr #IoT

Sofar I have been experimenting with LoRa and TTN using a Multitech MDot board and with a HopeRF RFM95W module connected to a Teensy, but I decided to try something else. Franz, one of the members of the TTN Nijmegen community, started experimenting with node-to-node communication using Dorji DRF1278F 433MHz modules. I’d like to support him in converting to 868MHz, so that he can post data to TTN once a gateway become available in his range.

The Dorji modules are currently among the cheapest LoRa modules available on Ebay. So some weeks ago I ordered a DRF1272F 868MHz module for about $8, which arrived this week.

The first surprise is that it has a 1.27 mm pitch header connector. The module has 13 contacts, but not all are required for the LMIC Arduino library. To make it more easy to handle, I made a custom break-out board that connects the required pins to a 2.54 mm pitch 8-pin header. Soldering the wires at 1.27 mm pitch was quite a challenge; you may want to use a magnifying glass, as those pads are tiny!

Based on the DRF1272F datasheet, the LMIC Arduino library documentation, and the Teensy pinout I connected it as follows:

Please note that I did not connect the RESET and the DIO2 pin, which would be needed for FSK.

I used the following snippet of code in my Arduino sketch to specify the pin mapping:

On the software side I am using Arduino 1.6.9, the LMIC library and the same sketch that I have been using with the RFM95W module.

Following all of this, this node is nicely sending packets to my TTN application.

TTN/LoRa using Dorji DRF1272F module