Category Archives: Home Automation

Home Automation – Automatic Garden Watering

An automatic garden watering system was my original goal for my home automation system, especially as this year we have had very sunny and dry conditions. I was out watering my plants nearly every night.

I have several different things I needed to water; raised beds with vegetables, a wall of strawberries, some fruit trees, and we tried our hand at potatoes this year as well.

Automatic Watering System - Beds

Automatic Watering System – Beds

Four zones fitted nicely with my four channel MOSFET board I had designed. There is a dedicated blog post about the process I went through to design and manufacture the MOSFET shields and you can buy them on Tindie for you own projects. 😊

I sell on Tindie

I designed a water manifold with four 12v solenoids which would give me four individually controlled watering zones and a pass-through connector so I could daisy chain additional controllers later as required.

I needed to split the watering zones up because my water pressure could not drive all the drippers and sprinklers at the some time, if they were all connected in series. You need a reasonable amount of pressure to get the mini sprinklers to work properly and you can’t drive more than 15-20 at once as the pressure drops too low.

I used Hoselock Easy Drip system to supply water to the plants and beds I needed to water. The system is simple to configure. You run a standard hose around the bed, and clip on sprinkler heads which pierce the hose and provide irrigation. There is also a micro drip system which uses smaller 4mm hose for pots. I used the Easy Drip for all the beds and Micro Drip for the strawberries.

Hozelock Easy Drip System

Hozelock Easy Drip System

Hozelock Micro Dripper

Hozelock Micro Dripper

Design

I built the manifold out of ¾” threaded pipe connectors and 12v solenoids. Next time, I might try making the manifold from soldered fittings, but the threaded fittings gave me the flexibility to change the design as I built it. I have also found some ready-made manifolds since building mine, so I might try those too next time.

Automatic Watering System Manifold

Automatic Watering System Manifold

I built a wooden box out of some old decking boards I had, so I could mount the manifold and controller on the fence.

Automatic Watering System Box

Automatic Watering System Box

The device would be in my garden, so I used a Wemos D1 Mini microcontroller with an external antenna to give me a bit of extra WiFi range. It will be powered by a 12v battery, so I mounted the Wemos and MOSFET shield in an IP60 weatherproof case, with a DC-DC step down convertor to give me 5v to power the Wemos and 12v from the battery for the solenoids.

The plan is to charge the battery from a small solar panel, so its completely wireless in the garden. The current draw is tiny. The solenoids only draw about 600mA each and they are only on for short amounts of time. Even without a solar panel to charge the battery, it would last maybe 2 weeks between charges.

Automatic Watering System Final Installation

Automatic Watering System Final Installation

The main water feed from the garden tap comes in on the right hand side via a manual valve so I can quickly turn off the water if I need to, without having to walk all the way back down the garden. I leave this on and connected all the time, so the watering system can water at any time of the day or night.

There are four watering zones, one on each solenoid. The four zones are;

  1. Potatoes
  2. Vegetables Beds
  3. Fruit trees
  4. Strawberry Wall

The last connection on the left is a pass through from the main feed, also via a manual valve, where I can either daisy chain another four zone controller, or attach a hose and hand held sprinkler for manual watering.

Testing

To test the controllers and manifold worked correctly before I installed it permanently, I wrote a simple script that turned on each channel sequentially, with an MQTT message, every 2 seconds.

I positioned the controller with its external antenna just on the edge of my house WiFi range, so it was as far up the garden as it could be, but still in range.

Automatic Watering System - Potatoes

Automatic Watering System – Potatoes

The automation is driven by NodeRed. I water each zone for 20 mins every morning at 6am. I can add more logic later if I need. There are all kinds of modules and sensors I could add to measure soil moisture or rain sensors and decide not to water if its been raining or the ground is already moist, but there’s no risk of over-watering anything at the moment, so it just waters every day for 20 mins.

In theory if the summer gets really hot, I could measure soil moisture and decide to add an extra watering cycle midday if the ground is really drying out in the sun. But that will be a phase two.

I also have a manual override using the NodeRed dashboard buttons, so I can manually turn zones on and off from my mobile phone.

Automatic Watering System NodeRed Flows

Automatic Watering System NodeRed Flows


Automatic Watering System NodeRed UI

Automatic Watering System NodeRed UI

The results have been amazing. The strawberries have really benefited for daily watering. We got a fantastic crop of potatoes too. Now the automatic watering system is in place we will increase the volume of plants next summer, now I’m confident they will all survive, and I don’t need to spend hours watering them every day! 😊

Lots of Strawberries

Lots of Strawberries

Design, Fabrication and Testing of a MOSFET Shield for a Wemos D1 mini ESP8266 Microcontroller

Design

I needed a MOSFET Shield for a Wemos D1 mini to drive solenoids and relays. I could not find anything suitable online, so I decided to design and build my own. The board size of a Wemos D1 mini is quite small (1″ x 1.3″) and part of that is the PCB antenna, so a shield should avoid covering the area over the antenna with copper or lots of components.

Wemos D1 Mini ESP8266 Development Board

Wemos D1 Mini ESP8266 Development Board

I wanted the shield to be the same size as the Wemos D1 mini. I need to be able to switch about 12v at about 2A. Most use cases I had were small relays and solenoids.

I found a very small dual channel MOSFET in a 2mm x 2mm package (FDMA1024NZ – Dual N-Channel MOSFET 20V / 5.0A). This MOSFET is so small I could fit two on the shield, giving a total of four channels.

Wemos D1 Mini MOSFET Shield 4ch v1.3 Schematic

Wemos D1 Mini MOSFET Shield 4ch v1.3 Schematic

Wemos D1 Mini MOSFET Shield 4ch v1.1 Board

Wemos D1 Mini MOSFET Shield 4ch v1.1 Board

Fabrication

I created the board design and ordered the PCBs and a solder stencil for the first prototype. The 2mm x 2mm package is very difficult, if not impossible, to hand solder, so the stencil would allow me to stencil the solder paste and hand place the components, before reflowing it in an oven.

MOSFET Shield for Wemos D1 mini before solder stencilling

Before solder stencilling

MOSFET Shield for Wemos D1 mini during solder stencilling

During solder stencilling

MOSFET Shield for Wemos D1 mini after solder stencilling

After solder stencilling

MOSFET Shield for Wemos D1 mini close up of solder stencilling and component placement

Close up of solder stencilling and component placement

MOSFET Shield for Wemos D1 mini v1.1

First prototype completed

The first version worked perfectly, but the 2mm x 2mm MOSFET was a little obscure and difficult to hand solder. In addition, JLC PCB had launched a pick and place PCB fabrication service which was very economical. I thought I’d try it for my MOSFET board, but the MOSFETs I was using were not supported. So I replaced the two obscure dual MOSFETs with four discrete MOSFETs which JLC support as a basic components.

Wemos D1 Mini MOSFET Shield 4ch v1.3 Board

Wemos D1 Mini MOSFET Shield 4ch v1.3 Board

The JLC PCB fabrication service built a batch which again all worked perfectly.

MOSFET Shields for Wemos D1 Mini v1.2

MOSFET Shields for Wemos D1 Mini v1.2

Testing

I needed to test the board design to ensure it could handle the current rating. The MOSFETs are rated at a maximum of 5A each. So, each individual channel should switch 5A. In addition all four channels can be connected together which would switch about 20A in total. I wanted to make sure the tiny PCB would handle this load. I designed the power traces on the PCB to be as wide as the physical dimensions of the board would allow.

I bought a 180W battery tester from BangGood to use as a variable load which could test up to 20A and 180W. This device has lots of useful features. You can configure it as a constant current load in 10mA increments. It measures voltage, current, power and even temperature using a plug in thermocouple, and displays all the readings in real time on a colour LCD. Its a very functional device for a very economical price.

To source 20A, I decided to use a lead acid battery. I don’t have a bench power supply that can easily provide 20A. I used thick 12AWG wire to connect the battery to the variable load and the shield under test.

MOSFET Shield for Wemos D1 mini Power Testing Setup

MOSFET Shield for Wemos D1 mini Power Testing Setup

The test setup consisted of;

  • A 12v lead acid battery
  • The variable load
  • The shield under test – with the MOSFET outputs shorted together

Power Testing Setup

Power Testing Setup

I planned to test each individual channel at 1A, 2A, 3A, 4A & 5A, while monitoring the temperature of the MOSFET, PCB traces and connectors. In addition, I want to connect all four channels together and test up to 20A.

The first few tests went well. Each channel can handle up to 5A. The MOSFETs get a little warm at 5A. If the board is used at maximum capacity for long periods, it would benefit from either forced air cooling or a small heat sink on the MOSFETs.

MOSFET Shield for Wemos D1 mini Power Testing Temperature

MOSFET Shield for Wemos D1 mini Power Testing Temperature

I struggled to test all channels to a total of 20A. The battery tester I had can only handle 180W, and the only convenient 20A source I had was a 12v lead acid battery. 12v @ 20A is 240W which is more than 180W, and the tester cuts out when it hits 180W.

I managed to test up to 16A with the lead acid battery setup, which was right on the limit of the 180W limit.

MOSFET Shield for Wemos D1 mini Power Testing 16A

MOSFET Shield for Wemos D1 mini Power Testing 16A

I had a small 2S LiPo at 7.2v and managed to complete a final test of 20A using this LiPo, but at 20A is the battery discharged very quickly and the voltage would drop to 6v very quickly and the tester cuts out at 6v to protect the battery from over discharge.

MOSFET Shield for Wemos D1 mini Power Testing 18A

MOSFET Shield for Wemos D1 mini Power Testing 18A

I’m confident the boards will operate to 5A per channel, to a maximum combined current of 18A as I managed to successfully test to both these levels. At higher currents the individual MOSFETs get hot and the Dupont header does. I think the header pins are only rated to 5A, so for 20A the board would need a redesign with more power pins to distribute the load. 4A per channel is way more than most of my projects need, so I’m happy with the design. If you really need to switch 20A for short periods of time, use a heatsink and solder the wires directly to the board rather than use pin headers and a Dupont connector.

Batch production

The shields were used in three of my home automation projects:

  • Automatic Garden Watering to control four water solenoids connected to garden hoses.
  • Immersion Heater Controller to control 2 high current relays to switch two 3kW hot water immersion heaters.
  • Automatic plant Pot Watering to control a small peristaltic pump to water pot plants based on moisture reading from a capacitive moisture sensor. This was the project that I added the analogue in header on the shield for. This allowed me to connect the moisture sensor and the peristaltic pump to the same shield.

Once the shields had been running in projects for a couple of months, without any issues, I decided to build a small batch to sell online. If I couldn’t find something similar online, then maybe others would like to buy these to use in their robotics or home automation projects.

MOSFET Shield for Wemos D1 mini v1.3 Panel for Fabrication

MOSFET Shield for Wemos D1 mini v1.3 Panel for Fabrication

The four channel MOSFET shield can be purchased here on Tindie.

I sell on Tindie

Final Specification

  • Dimensions : 1″ x 1.3″ x 0.063″ (25.4mm x 33.0 x 1.6mm)
  • Four MOSFETs : AO3400A – 30V N-Channel
    • Maximum Drain-Source Voltage : 30v
    • Continuous Drain Current : 5A
  • GPIO pins used : D5 (GPIO14), D6 (GPIO12), D7 (GPIO13) & D8 (GPIO15)
  • ADC pin A0 available on 0.1″ header with power pins (selectable 3.3v or 5v)

Future revisions

I have already starting thinking about additional features that could be useful.

Using four digital GPIO pins to control the MOSFETs is sometimes a pain as the GPIO pins are shared with other features on the microcontroller. The D5, D6, D7 & D8 pins used on the shield are also the SPI port, so when the MOSFET shield is connected you cannot use SPI at the same time.

An improvement would be to use a I2C device to control the four MOSFETs rather than discrete GPIO pins. Multiple I2C devices can be connected in parallel to the same pins, so if I switched the shield to use I2C you could stack other shields in parallel and all of them would work.

There is a 4-bit I2C I/O expander IC (PCA9536) which could facilitate this. The board layout would be very tight to fit this additional chip on the same top layer. I could try and place it on the bottom layer, but a dual sided board is more expensive and complex to produce.

Or I could also try and add solder jumpers on the bottom layer to allow different GPIO pins to be user selectable.

I’m interested in any feedback on the board or any additional feature requests you would like to see. Leave your feedback in the comments section below.

Home Automation – Temperature Sensors

I wanted to monitor internal and external temperatures as part of my home automation, so I decided to use Wemos D1 mini boards for this, running Tasmota, as they are small, feature rich and really inexpensive (about $2 each).

The Wemos D1 mini is a fully functional ESP8266 board with built in WiFi antenna, 11 GPIO pins that support protocols like SPI & I2C, an analog input and USB interface. There are also many shields that provide lots of different features like temperature sensors, OLED Screens, Relays, LEDs, etc. You can buy the boards and shields on AliExpress. I particularly like the OLED displays and the temperature sensor board.

I initially designed a custom PCB for the old ESP01 development boards, which contained a USB to 3.3v power supply and space for a DS18B20. However, most of the ESP01 boards only have 512kB of Flash which is too small to easily enable over-the-air updates for the firmware. So, I quickly switched to the Wemos D1 Mini boards instead.

ESP01 DS18B20 Temperature Sesnor Board

ESP01 DS18B20 Temperature Sesnor Board

 

Although it is trivial to attach a 1-wire DS18B20 temperature sensor to the Wemos, a shield makes the wiring neater.

Wemos SHT30 Temperature and Humidity Sensor Shield

Wemos SHT30 Temperature and Humidity Sensor Shield

 

The Wemos SHT30 Temperature Shield contains a SHT30 sensor, which provides accurate temperature and humidity readings over an I2C interface. Configuring the temperature sensor in Tasmota is trivial. Just configure the I2C pins in the admin interface and temperature and humidity is displayed on the home page.

Tasmota I2C Temperature Sensor Config

Tasmota I2C Temperature Sensor Config

 

The Tasmota code automatically searches for all connected I2C sensors when it boots and displays anything it finds. You do not need to tell Tasmota which sensor it is. A full list of support sensors in Tasmota can be found here.

 

Tasmota Showing SHT30 Sensor Data

Tasmota Showing SHT30 Sensor Data

Note: To get sensor support you will need to flash the devices with the tasmota-sensors.bin binary, instead if the generic tasmota.bin file. Sensor support was recently moved into its own binary to make the default binary smaller.

Reading the data – HTTP

You can query the data directly over HTTP using the url :

http://192.168.1.20/cm?cmnd=status%208

(Substituting for your IP number)

The response is a JSON structure containing all the sensor data.

{"StatusSNS":{"Time":"1970-01-09T03:28:52","ANALOG":{"A0":8},"SHT3X-0x45":{"Temperature":20.5,"Humidity":63.1,"DewPoint":13.2},"TempUnit":"C"}}

On a Raspberry Pi you can extract raw data values using jq to navigate the JSON Structure.

curl -s http://192.168.1.20/cm?cmnd=status%208 | jq '.StatusSNS."SHT3X-0x45".Temperature'

18.1

Note: you must encase the “SHT3X-0x45” in double quotes. It is an artefact of the jq library, it does not like the -0x in the middle of the sensor name. I don’t really know why … it works fine for sensors that don’t have funny characters in the middle. E.g. ‘.StatusSNS.MAX31855.ProbeTemperature’)

Reading the data – MQTT

You do not need to read the temperature directly from the device if you are using MQTT. By default Tasmota automatically sends “Telemetry” messages out over MQTT every 5 minutes containing all the sensor data, which can be received and processed by NodeRed.

An example MQTT “TELE” message:

{"topic":"tele/temp01/SENSOR","payload":"{\"Time\":\"2020-07-01T13:17:44\",\"SHT3X-0x45\":{\"Temperature\":26.0,\"Humidity\":47.4,\"DewPoint\":13.9},\"TempUnit\":\"C\"}","qos":0,"retain":false,"_msgid":"d1a72fd2.4d6fc"}

I configured a dashboard gauge in NodeRed to show the temperature data in real time for my internal and external temperature sensors.

Temperature Gauge NodeRed Flow

Temperature Gauge NodeRed Flow

 

The function to extract the payload strips all the other information from the message and just returns the value in the payload ready for the dashboard gauge to display.

msg.payload = msg.payload["SHT3X-0x45"].Temperature;
return msg;

 

Temperature Gauge NodeRed Dashboard

Temperature Gauge NodeRed Dashboard

Voila a simple, real-time, temperature gauge on my phone over MQTT.

Home Automation – MQTT, Mosquitto, Node Red, Sonoff & Tasmota

There several things in my house I have been meaning to automate for a while. Some are obvious and simple, like lights and lamps around the house and the water fountain in the garden, others are more complex, like the Economy 7 hot water immersion heater and an automated garden watering system.

After reading a lot of forums and watching a lot of YouTube videos, it was obvious that MQTT was at the heart of any DIY home automation system.

YouTube channels, like Andreas Spiess and SuperHouseTV were a hugely useful resources.
I decided to use a Raspberry Pi running Mosquitto as the MQTT broker and NodeRed for some automation.

There are plenty of tutorials online on how to install these and it’s very simple.

For Mosquitto:

apt-get install mosquitto
apt-get install mosquitto-clients

For NodeRed, the instructions are here.

bash < (curl -sL https://raw.githubusercontent.com/node-red/raspbian-deb-package/master/resources/update-nodejs-and-nodered)
node-red-start

MQTT has a simple “Publish & Subscribe” model (sometimes called “PubSub”). Things can publish messages on a topic which are sent via the broker to anything that has subscribed to that topic. You can subscribe to a particular topic, or to all messages, or filter the topic using wild cards and expressions. It’s very flexible and there is a huge ecosystem of devices that support MQTT.

I setup a simple local software test on the Raspberry Pi to check everything was working after I rebooted. By installing the mosquito clients on the Raspberry Pi I can publish and subscribe using command line tools.

I opened two separate SSH windows, in the first I subscribed to a test topic called “test/message”

mosquitto_sub -t "test/message"

This command will stay running and output any messages that have the topic name “test/message”

In another windows I published a message on that topic with the payload value “hello”

mosquitto_pub -t "test/message" -m "hello"

in the first subscription windows I see the message “hello” appear. It’s all working!

pi@localhost:~ $ mosquitto_sub -t "test/message"
hello

After watching a lot of Andreas and SuperHouse on YouTube, it was clear that the simplest way to automated devices in the home using MQTT was with a Sonoff device, and to reflash this device with an open source firmware called Tasmota.

The Sonoff devices do come with a firmware that provides some simple automation and remote control, but it is not open source. Who knows what data it is collecting. It also needs a public internet connection, whereas a local MQTT Server and Tasmota means all my devices stay on the local network and do not need an internet connection to function.

Sonoff devices are inexpensive, well made and easy to hack; plug sockets, switches and other devices that are all based on the ESP8266 chip. Using these devices Theo Arends and others built an open source MQTT based firmware for Sonoff devices called Tasmota.

Tasmota Code is here on GitHub.

Tasmota Documentation is here.

Tasmota

Tasmota has pretty much everything you need already built in to it, in a very small binary. It includes MQTT support and HTTP management interfaces. Over the air updating means you can reflash the device with new firmware releases using the HTTP interface, rather than having to connect a serial cable. It also has support for dozens of common sensors, like 1-wire temperature sensors, RGB LEDs, etc, all supported out of the box in the code.

Almost all the Sonoff devices can be reflashed to run Tasmota, plus a long list of other hardware, including other ESP8266 based devices and development boards. A full list of supported hardware and sensors is on the Tasmota Template Repository.

I bought some Sonoff S20 sockets. These are mains plug/socket combos than allow you to plug in pretty much any mains powered device into a domestic mains plug and have control over it using home automation. The sockets can switch 10A (about 2kW in the UK) and they have a manual override switch so you can manually turn the device on and off at any time as well.

The initial flashing process is very simple, but you need to take the cover off the Sonoff device, and these are mains voltage when they are plugged in. So do this at your own risk, and watch some YouTube examples first. They do not need to be, and should not be, plugged in to the mains while you flash them. Only plug them in after you have disconnected your programming cable and replaced the covers.

What this video from SuperHouseTV which gives detailed instructions.

I made simple programming lead from a USB to Serial dongle to program the boards and I didn’t solder headers in to the Sonoff device, I just pushed the pins from the lead in to the PCB hole while it programmed and held them there manually. It takes less that a minute to upload the new Tasmota firmware and once it’s running you can do everything else through the web interface, so you should never need to open the device again.

You need to install the esptool.py on your laptop / computer, which is used to transfer the firmware binary file to the ESP8266 over a serial cable. Once you have identified the com port your serial cable is attached to, the command line is simple.

Download the latest Tasmota firmware from GitHub if you scroll down in that page you’ll find a long list of binary files to download. There are lots of binary files to choose from, but don’t let this confuse you. I have yet to need anything other than the basic binary. It supports all the common functionality you need, and if you need something specific later, you can change the binary over the air.

Just download tasmota.bin from the release page, and copy it to your local directory. I like to add the version number of the release in the filename, so I know which file is which version next time I need to flash something. In this example I named tasmota.bin to tasmota-8.3.1.bin.

Then run esptool.py to upload the binary file to the ESP2866 chip on the Sonoff device.

cd Projects\Sonoff\Tasmota
esptool.py -p COM11 write_flash --flash_size 1MB --flash_mode dout 0x00 tasmota-8.3.1.bin

You will need to substitute the correct COM port for your serial cable and the correct filename for your tasmota.bin.

While flashing via the serial cable, you should see something like this:

esptool.py v2.6
Serial port COM11
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
MAC: DE:AD:BE:EF:12:34
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Compressed 519920 bytes to 355646...
Wrote 519920 bytes (355646 compressed) at 0x00000000 in 31.7 seconds (effective 131.2 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...

Once the Sonoff device is flashed with Tasmota, you can reboot it, and you should find a new WiFi SSID called “tasmota_xxxx” where “xxxx” is the last part of the devices MAC address.

  • Connect to this access point “tasmota_xxxx” on your phone or laptop.
  • Browse to 192.168.4.1 on your phone or laptop and you should get the default Tasmota configuration screen.
  • Add the WiFi SSID & Password for your house network, click save and reboot.
  • Once it has rebooted, it will connect to the house WiFi network and you should be able to find the DHCP IP address in your DHCP server.
  • Once you know the local IP you can reconnect to your house WiFi on your laptop and connect directly to the Tasmota device in a browser using its IP number.

Screenshot of the configuration screen in Tasmota where you enter your WiFi details

Screenshot of the configuration screen in Tasmota where you enter your WiFi details

You need to configure a few things in Tasmota to enable MQTT. You need to set the MQTT broker IP address and tell Tasmota what the hardware device is so it know which GPIO pins control which functions.

You can configure this in the web interface. Browse to your device IP number and from the menu select “Configuration” | “Configure MQTT”. Set the “MQTT Host ” to the IP number of your Raspberry Pi Mosquito MQTT Broker you installed earlier.

If you are using a Sonoff S20 plug, from the menu select “Configuration” | “Configure Module” | Module Type = “Sonoff S2X”

Save and reboot and that’s pretty much it. The Tasmota device is fully configured and ready to receive MQTT Messages.

Once you are familiar with the web user interface, it is sometimes quicker to configure your devices via the console. There is a full list of Tasmota commands here.

Once you have flashed your device, do not disconnect the USB cable. Open a serial terminal window with 115200 baud (8N1) and you will have access to the command console.

You can enter you local WiFi credentials using the following syntax :

backlog ssid1 YOUR_WIFI_NAME; Password1 YOUR_WIFI_PASSWORD;

Your device will reboot.

The given IP address will be visible in the serial console output:

00:00:00 Project tasmota Tasmota Version 8.3.1(tasmota)-2_7_1
00:00:00 WIF: Connecting to AP1 HouseWiFi Channel 6 BSSId DE:AD:BE:EF:12:34 in mode 11N as tasmota_3B7DE8-7656...
00:00:03 WIF: Connected
00:00:03 HTP: Web server active on tasmota_3B7DE8-7656 with IP address 10.1.0.73
16:30:48 RSL: tele/tasmota_3B7DE8/INFO1 = {"Module":"Sonoff Basic","Version":"8.3.1(tasmota)","FallbackTopic":"cmnd/DVES_3B7DE8_fb/","GroupTopic":"cmnd/tasmotas/"}
16:30:48 RSL: tele/tasmota_3B7DE8/INFO2 = {"WebServerMode":"Admin","Hostname":"tasmota_3B7DE8-7656","IPAddress":"10.1.0.73"}
16:30:48 RSL: tele/tasmota_3B7DE8/INFO3 = {"RestartReason":"External System"}
16:30:48 RSL: stat/tasmota_3B7DE8/RESULT = {"POWER":"OFF"}
16:30:48 RSL: stat/tasmota_3B7DE8/POWER = OFF
16:30:52 RSL: tele/tasmota_3B7DE8/STATE = {"Time":"2020-06-30T16:30:52","Uptime":"0T00:00:11","UptimeSec":11,"Heap":29,"SleepMode":"Dynamic","Sleep":50,"LoadAvg":19,"MqttCount":0,"POWER":"OFF","Wifi":{"AP":1,"SSId":"HouseWiFi ","BSSId":"DE:AD:BE:EF:12:34","Channel":6,"RSSI":100,"Signal":-39,"LinkCount":1,"Downtime":"0T00:00:05"}}

Yon can either setup the device with extra commands over the serial cable, or do the same in the web console :

backlog MqttHost 10.1.0.90; NTPserver 10.1.0.110; Timezone 0; TimeDST 0,0,3,1,1,0; TimeSTD 0,0,10,1,2,0;
backlog SetOption56 1; SetOption57 1; GroupTopic alldevices;
etc.

Most commands need a reboot, but using the console is so much quicker that clicking through  the web interface.

Testing

I tested mine with a simple lamp plugged in to the socket and the socket plugged in to the mains.

By default all Tasmota devices have a “Fallback” topic. This is an MQTT topic which is unique to that device. You do not need to manually configure it (it is derived from the device mac address) and it is listed in the information page on the device.

MQTT Fallback Topic cmnd/DVES_3DDEE5_fb/

The Tasmota / Sonoff device is automatically subscribed to this topic. So, if you send an MQTT Message to this topic from anywhere, it will control the device.

From the Raspberry Pi terminal enter this command using your fallback topic details.

mosquitto_pub -t "cmnd/DVES_XXXXXX_fb/POWER" -m "ON"
then
mosquitto_pub -t "cmnd/DVES_XXXXXX_fb/POWER" -m "OFF"

The lamp will go on and off ! Genius ! 😊

I flashed about a dozen Sonoff S20 plugs and scattered them around the house on various lamps and devices I needed to control. I use them to control lamp in rooms, the lights on my fish tank, the pump in the garden fountain, etc. Nearly everything needs to come on at a particular time in the morning and go off at night.

Automation

I used NodeRed to automate my smart sockets.

Use the fallback topic for the NodeRed topic name in both elements with /POWER at the end. E.g. “cmnd/DVES_3B7DE8_fb/POWER”

Use the payload “ON” or “OFF” to turn the device on or off.

The Inject node can be set to inject at a specific time, or day, or repeat, etc.

I ran this for a few weeks and none of my devices missed a message. They all came on and went off as defined in NodeRed. The Sonoff devices are stable as are Mosquitto and NodeRed.

After a bit more reading, I discovered a custom node call BigTimer, which everyone seems to use instead of the built in “Inject” node. This can be installed through the interface. Just go to “Manage Palette” in NodeRed and search for “bigtimer” which will find “node-red-contrib-bigtimer” and install it.

This combines on and off messages in a single node, making the workspace a lot less cluttered, plus it has all kind of other useful features like “sun rise” and “sun set” which takes your GPS location and works out when it will get dark. Useful for controlling fish tank lights or outside lights.

You can also define certain days or months the command will operate in, useful for having your outside watering system only on during the summer months, for example.

I replace all my inject nodes with BigTimer and I have been using that without issue ever since.

My garden fountain is on during the day at sunrise, and automatically goes off at sunset !

The final nice to have is a mobile app that I can use to manually override the automation if required and switch things on and off manually. The easiest way to do this initially is to use the Dashboard feature of NodeRed. The limitation of this is that I can only access it from within my local network as my NodeRed server is not open to the public on my firewall. However this is acceptable for the time being. We can change it later and add more feature. There are plenty of full blown home automation interfaces I can add later, including Google Home automation with voice control.

The Dashboard feature of NodeRed can be installed using the Palette Manager, or following the instructions on the dashboard website.

You can add gauges, buttons, switches, etc. To start with, I added a switch for each socket. You can just add the switch to the flow and connect it to an MQTT topic. This works, but if you manually change the state of the switch outside of NodeRed, by pressing the physical button on the socket for example, the dashboard element wont know about this and update the state.

To fix this you have to subscribe to the “stat” status messages coming from Tasmota on the device and feed them back in to the dashboard switch element. I added a simple function before the dashboard switch element to change the topic from the “stat” topic it receives to a “cmnd” topic the switch needs to change state.

For example, For SocketA I subscribed to “stat/socketa/POWER” in NodeRed and the function after this node changes the topic to “cmnd/socketa/POWER” and feeds it in to the dashboard element. The output of the dashboard element send the message out as MQTT again when the switch is pressed.

msg.topic = "cmnd/socketa/POWER";
return msg;

My final NodeRed flow looks like this for all my sockets. I have a dashboard flow for each one, and a BigTimer node for those that I need to automate.

NodeRed flow for control of Sonoff Sockets

NodeRed flow for control of Sonoff Sockets

Screenshot of the NodeRed Dashboard interface on my phone.

Screenshot of the NodeRed Dashboard interface on my phone.

Home automation phase one complete ! 🙂