Sonoff RF Bridges are great to take every day houshold remotes, alarm systems, passive IR seasons etc , and pass the codes they transmit via MQTT messages.
These bridges can also be flashed with the Tasmota open-source firmware used for Home Automation.
Sonoff 433 Mhz BridgeSerial Port on the 433 Mhz BridgeFlashing with a Raspberry Pi
Device Definition json file is in the github repository along with the source code. This can be imported into Azure IoT Central and the views generated.
Azure IoT Central makes it easy to connect, monitor, and manage your IoT devices at scale. With the IoT Central V3 connector, you can trigger workflows when a rule has fired, and take actions by executing commands, updating properties, getting telemetry from devices, and more. Use this connector with your Azure IoT Central V3 application.
Due to the dynamic nature of Azure IoT Central, using the connector is not quite straight-forward. To use the Azure IoT Central connector in Canvas apps you need to enable two features in the settings of the application.
These are:
Enhanced formula bar
Dynamic Schema
Enabling these two features allows Power Apps to understand the resulting schema from a call to IoT central. “Capture Schema” will be enabled on the formula bar.
Power Apps Canvas Settings: Enhanced Formula BarPower Apps Canvas Settings: Dynamic SchemaFormula bar: Schema Capture
Power Automate
Power Automate is a lot simpler to get to work. It automatically understand the dynamic schemas of IoT Central.
I control a few devices from the Internet, but I don’t want all devices exposed and connected to IoT Central. One solution is to build a gateway locally which routes request messages to switch things on or off to the correct device locally.
In this post we will look at how to send commands from IoT Central and route them using Node-RED to the automation device via MQTT.
Home Automation Gateway Architecture
This architure uses Node-RED as a gateway, and then uses Eclipse Mosquito as a MQTT server. The Grow Light and Air Conditioner in the diagram is an off the shelf Sonoff POW-R2 device flashed with Tasmota.
With Node-RED you can visually map the flow / sequence of events. Node-RED supports Azure IoT Hubs and Azure IoT Central, so it’s perfect for this job to do quickly and easily without having to write code.
Gateway device created in IoT Central’s Command Capabilities
In Azure IoT Central we have a single device linked with a command. The command accepts a parameter, which will be the device name / topic name on the local MQTT server.
Executing a command on IoT Central
The diagram above shows the command with the parameter.
Defined Methods to IoT Central Commands
The Node-RED Azure component supports Direct Methods. These are commands that you can directly invoke on a device. In this case, the device is the gateway itself created within Node-RED.
It supports two methods (as per Azure IoT Central template)
turngatewaydeviceon
turngatewaydeviceoff
Switch to determine flow based on Direct Method Invoked from IoT Central
With a Node-Red switch statement we can controll the flow with whichever method name was invoked from IoT Central.
Switch Home Automation On flow
If it’s the “DeviceOn” flow, then the device parameter name (payload) is used to build up the topic for the Sonoff device via MQTT. The payload of the message will be “on”.
Switch Home Automation Device Off Flow
If it’s the “DeviceOff” flow, then the device parameter name (payload) is used to build up the topic for the Sonoff device via MQTT. The payload of the message will be “off”.
The Sonoff devices are great, but I prefer to use everything within my home and home automation setup to be fully under my control. Tasmota is a great way of doing just that.
I found the easiest way of flashing devices with Tasmota is using a raspberry pi. I’ve done a quick writeup on how to do this.
Choose Interfacing OptionsConfigure SerialDisable login shell via serialEnable serial port hardwareSerial setup complete
Connect the Raspberry Pi to the Sonoff Device
Raspberry Pi Pinouts (Serial)
The TXD (Transmit) and RXD (Receive) pins are marked on the raspberry pi. We can use these to communicate serially with the Sonoff Device to flash it with the Tasmota firmware.
Sonoff POW R2 Device
Each Sonoff device has pins allocated to reflash the device. These boards usually don’t have headers attached. Here I soldered one to the board.
The important pins are VDD, TX, RX and GND.
Flashing the device with a Raspberry Pi
Connect VDD to an external power supply. The Raspberry Pi will not be able to power the device off it’s own pins. I used an external bench power supply. Ensure the voltage is 3.3V.
Connect the GND on the power supply to both the Raspberry Pi Ground Pins and the Sonoff device’s GND pin
Connect the TXD on the Raspberry Pi to the RX Sonoff pin and connect the RXD on the Raspberry Pi to the TX Sonoff pin.
Eclipse Mosquitto is an open source (EPL/EDL licensed) message broker that implements the MQTT protocol versions 5.0, 3.1.1 and 3.1. Mosquitto is lightweight and is suitable for use on all devices from low power single board computers to full servers.
The MQTT protocol provides a lightweight method of carrying out messaging using a publish/subscribe model. This makes it suitable for Internet of Things messaging such as with low power sensors or mobile devices such as phones, embedded computers or microcontrollers.
Running Mosquitto is easiest in a Docker container. This is really easy to set up.
Node-RED is a programming tool for wiring together hardware devices, APIs and online services in new and interesting ways.
It provides a browser-based editor that makes it easy to wire together flows using the wide range of nodes in the palette that can be deployed to its runtime in a single-click.
Running Node-RED is easiest in a Docker container. This is really easy to set up.
ScaleConf was an awesome 2 day conference. https://scaleconf.org/ In is held annually at Kirstenbosch, which is an amazing venue. There were some really interesting talks too!
I was lucky enough to this year be helping out at the Microsoft booth. I’m always in my element to be able to chat to the community about anything developer related.
It didn’t quite end up like that, and we ended up talking about what was requested, which was great. In my case, not only did I get to chat about Bots and ML .NET, but also got to speak about Xamarin and IoT too, which for me is always just plain awesome!!!
I had an incredible, but exhausting time at Microsoft Ignite the Tour Johannesburg. It was an amazing experience. I got to speak about Xamarin, AI and IoT, it doesn’t get much better than that. π
There is demo code for taking Cross Platform reach to the extreme. For one code base you can target, iOS, Android, Android Things, Tizen, Blazor (Web Assembly), GTK (Linux, Windows, MacOS).
What was really cool. The @JHBMSDUG user group was showcased at the event. Lou van der Bijl, Matthew Leibowitz and Dustyn Lightfoot did amazing jobs!
On the big stage πThe Demo booths were amazing. 2 Sessions each of speaking 4 hours about Xamarin, AI and IoT. Happiness. π
It was a real privilege being a small part of this event. The “AI Hack For Good” event was all about using AI to do something positive for social good.
It was also great fun being a mentor and helping to enable teams to complete their solutions using whichever technology they chose. (.NET, Java, PHP, Python, JavaScript, Swift, Kotlin)
Microsoft the Home of AIRed Bull was handy IoT Edge with Cognitive Services All hard at work The awesome organization team
I did my part to improve laptops π
Twitter Verse
It was truly inspiring being a small part of the "AI for Good Hack" last week in Johannesburg. Working with all these amazing teams, out to do good in the world with #ai was an incredible experience. Hope to see you at the next hack! #azure#python#dotnet#java#swift#kotlinpic.twitter.com/KCu7bSE4xT
The winners trophy of the #MSAIHACK at @MicrosoftSA went to Azure Gremlins. Innovative use of multiple features of @Azure to identify Fake News. Streaming services, sentiment analysis, @AzureML, @AzureCosmosDB, Bing Search API. Very impressive delivery in a short space of time!! pic.twitter.com/YibHDt0jzj
It was truly inspiring being a small part of the "AI for Good Hack" last week in Johannesburg. Working with all these amazing teams, out to do good in the world with #ai was an incredible experience. Hope to see you at the next hack! #azure#python#dotnet#java#swift#kotlinpic.twitter.com/KCu7bSE4xT
Team #SIGNificant take home R20 000 for their second place position. They worked on a solutions that uses AI to help translate and understand sign language #MSAIHackpic.twitter.com/659u1jxQZP