Currently my Internet of Things Things are quite limited, in my house I have a DIY DHT22 powered Temperature & Humidity Sensor and Phillips Hue lighting. However soon providing everything goes to plan I should be moving out of rented accomodation into my own home which greatly improves the flexibility for home automation and cool IoT devices. One theme in common with most Internet of Things Things appears to be the use of radio to a hub of some sort rather than hundreds of ESP8266 modules all over the place, and this of course becomes an attractive proposition as low powered but low bandwidth radio can easily achieve better range compared to WiFi and you can have a much higher density of IoT devices multiplexed on some radio technology in comparison to connected WiFi devices on consumer grade WiFi access points.
After a bit of research I decided I should start experimentation with this concept and I stumbled accross LoRa, low power, wide area networking for IoT usage. LoRa is particularly attractive because of The Things Network (TTN), an open network of LoRa gateways which allows your thing to latch on to any TTN LoRa gateway and start transmitting or indeed recieving it’s data, it’s also attractive as LoRa connected devices can be made uber cheap with modules as low as around £10 on eBay from China. My first intention was to convert my DHT22 humidity sensor to a LoRa based device, so I researched if I could use a nearby TTN LoRa gateway for this purpose. Unfortunately the closest gateway is a good 5 miles away from my house and although LoRa has proven to have very good range when line of sight can be achieved and with carefully planned conditions I knew it was almost impossible to contact this gateway from my house purely because of the landscape and the fact in the UK most TTN LoRa gateways are limited range DIY devices. Further more there are no LoRa gateways in the area I plan on moving to, so to go down the LoRa route I’d need to host my own gateway long term anyway.
Back to the drawing board, before I could convert my DHT22 ESP8266 powered sensor to LoRa I’d need to establish my own LoRa gateway. Initially this seemed to be a huge blocker, although the LoRa modules for use in IoT devices are cheap, a decent LoRa gateway seemed to be in the region of £200 for a compliant 8 channel device. Then I found the saviour Andreas Spiess a YouTuber from Switzerland with a selection of LoRa based experiments on his channel. He documented how he found a blog detailing the creation of a cheap 1 channel LoRa gateway using a Raspberry Pi and a cheap LoRa transiever module, he also explains the limitations of a 1 channel gateway, for example on your connected things you need to force 1 channel operation and you will be able to multiplex less devices. However for the low number of devices I plan on creating I am sure this will provide a cheap entry point and with the heads up from Andreas reducing alot of headaches along the way.
So I ordered the parts to start building a single channel gateway. Here is the shopping list, I already had some of the parts laying around in my electronics box… Of course if you would like to replicate the project you’ll need some tools like wire strippers, a soldering iron and so on.
- 1x Raspberry Pi
- 1x Raspberry Pi Power Supply
- 1x MicroSD Card (8GB+)
- 1x RFM95W LoRa Transceiver Module
- 8x Female to Female Jumper Wires
These items are due to arrive over the next couple of days, then I will start to build my single channel LoRa gateway and I’ll document progress as I go. Once the gateway is online I’ll order a few other LoRa modules and start playing with sending and receiving packets on a breadboard to ensure it is working as expected.