IoT with Sub-1 GHz Sensor Network
The idea is to have a local network of sensors connected to a hub. Obviously, I'd like to interface those sensors with Node-RED, which offers native support for MQTT and JSON, with an off-the-shelf protocol I could rely on.
Candidates for the radio include WiFi, Bluetooth and sub-1 GHz. The low power requirement rules the WiFi solution out. Both Bluetooth and sub-1 GHz fit for the low volume of data transferred. However, Bluetooth has a limited range and do not cross walls. So the sub-1 GHz remains the recommended option.
However, sub-1 GHz doesn't include a TCP/IP stack, on which MQTT relies. Luckily, there are specific protocols for sensors, but they require a gateway so they can talk with the MQTT broker. One the MQTT side, there is a variant called MQTT-SN for sensor network.
Texas Instruments has two evaluation kits with a gateway for sub-1 GHz sensors.
Form left to right, the CC1310 LaunchPad with the Sensors BoosterPack, and the CC1350 LaunchPad used as a BoosterPack on top of the CC3220SF LaunchPad.
So I asked for help and get some pointers from the E2E forum. All the application notes were updated to release A and I was able to complete the
On the right, the web-page shows the connected CC1310 LaunchPad with the temperature.
However, I wasn't able to connect to IBM Cloud or to a local MQTT broker.
Form left to right, the CC1350 SensorTag, the CC1350 LaunchPad connected through USB to the BeagleBone Black.
I failed to set the third-party services despite the instructions provided by Texas Instruments, and so I couldn't complete any of the demos.
So I asked for help and get some pointers from the E2E forum. Actually, there is a parallel application note with a procedure to set a 802.15.4 star network and run a web-service on a local machine.
On the right, the web-page shows two nodes, one CC1350 SensorTag and one CC1310 LaunchPad.
However, I wasn't able to figure out how to connect it to a MQTT broker.
So I turned to another solution based on the Moteino boards from LowPowerLab. The boards are very compact and combine a sub-1 GHz radio (433, 868 or 915 MHz) with an ATmega328.
The radios are provided by the modules RFM69 and RFM95/96 from HopeRF, based on the SX1231and SX127x transceivers from Semtech.
The boards come with an extensive suite of libraries, for radio, EEPROM, power management, OTA upload.
This solution relies on MQTT-SN, and comes with all the required examples prepared by Rodrigo Méndez.
There are two sketches, one for the nodes and another for the bridge. They run on the same Moteino boards.
Form left to right, the Moteino node, the Moteino gateway connected through USB to the Raspberry Pi.
The application for the gateway runs on the Raspberry Pi.
Despite all the buzz around IoT and home automation, I'm surprised to find a limited offer of solutions, and the instability of most of them. I've faced unexpected issues that lead to half-successes, with the Aquila and Moteino as a notable exception.
If home automation is the new main trend, there is ample room for easy-to-use and robust solutions.
I haven't tested other solutions like CoAP or ZigBee.
Posted: 15 March 2018
Updated: 04 April 2018, 12 April 2018, 11 July 2022