Tasmota
Tasmota is an open source firmware for the ESP8266 and ESP32. It is mostly used for home automation devices, but can also be loaded on any other ESP device. It comes with support for a wide range of peripherals 'out of the box' and makes interacting with sensors via WiFi extremely easy as a result.
Flashing Tasmota
Obtain ESPTool and the latest Tasmota binary. Use ESPTool.py to erase and load Tasmota via serial.
Here is what I did to flash a Wemos D1, for example.
$ python -m esptool --port /dev/ttyUSB0 erase_flash
esptool.py v3.0
Serial port /dev/ttyUSB0
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
Crystal is 26MHz
MAC: 50:02:91:fe:9d:a4
Uploading stub...
Running stub...
Stub running...
Erasing flash (this may take a while)...
Chip erase completed successfully in 8.6s
Hard resetting via RTS pin...
$ python -m esptool --port /dev/ttyUSB0 write_flash -fs 1MB -fm dout 0x0 tasmota.bin
esptool.py v3.0
Serial port /dev/ttyUSB0
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
Crystal is 26MHz
MAC: 50:02:91:fe:9d:a4
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Compressed 613568 bytes to 438208...
Wrote 613568 bytes (438208 compressed) at 0x00000000 in 38.7 seconds (effective 126.8 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...
Configuration
After a factory reset, you will need to configure its WiFi settings manually by connecting to the WifiManager created access point. After it connects to the proper network, connect to it again through a web browser.
The following section applies to my own network and setup. For my own network, because the IoT devices are all in its own isolated network, I need to do a SSH tunnel in order to access the web interface. This is done by running: ssh -L 8080:192.168.1.x:80 root@iot-router and then connecting to localhost:8080 in a web browser. In the web interface, there are a few things that needs to be configured in order for it to work properly with the NodeRED/MQTT service outside of the IoT network.
- Setup the device template. Remember to check off 'activate' or else the template won't get applied.
- Configure MQTT. Set the host as
mqtt, port as1883, topic as the device name, and the prefix astasmota/%topic%/. The mqtt hostname resolves to the MQTT server and the IoT router allows MQTT traffic on port 1883 to leave the network to this server.
MQTT and hostname
When configuring the Tasmota hostname and MQTT strings, you may substitute variable names. This table outlines what you can use.
| Description | What you type | What you get |
|---|---|---|
| %06X | 0353C0 | |
| last 4 digits of mac | %04d | |
| hostname | %s | |
| MQTT prefix | %prefix% | One of: cmnd, stat, tele
|
| MQTT topic | %topic% | User defined. Eg: WP5-1
|
Rules
Rules are sets of commands that should run when a specific condition is met. They are a way to program user defined behaviors to Tasmota without requiring a recompile. The ability to write rules allow for interesting behaviors between sensors and peripherals, such as updating an attached display when sensor values change.
Rules are defined within a rule set. Tasmota out of the box has 3 rule sets called rule1, rule2, and rule3. Any number of rules can be placed in each set (though, limited by the device's memory, but the documentation says at least 1000 bytes). Rule sets can be enabled or disabled, which also enables or disables any rules within. This allows for entire behaviors to be enabled or disabled simply by enabling or disabling a rule set.
Quick start with rules
Frequently, we want to do something with a sensor reading. In the case of a CO2 monitor, we could possibly want to update a display when the PPM value changes.
Rule1
on MHZ19B#CarbonDioxide do DisplayText [zc1l1]%value%ppm endon
Rules are always defined within a rule set and always begin with 'on' and end with 'endon'. In this example, the rule is defined within rule1 and would run DisplayText whenever the sensor's CarbonDioxide metric changes. We can add additional rules within rule1 by appending additional rules as a list. In another example with the INA219, we could write the following rules which will write the voltage, current, and wattage value to a display:
Rule1
on INA219#Voltage do DisplayText [c1l1]V %value% V endon
on INA219#Current do DisplayText [c1l2]I %value% A endon
on INA219#Power do DisplayText [c1l3]P %value% W endon
For the rules to take effect, enable the rule set:
rule1 1
For more complex rules that need to run multiple commands, chain them together with the backlog command. Rules can also enable or disable entire rule sets to enable or disable some behavior. Case in point, from one of my other projects, we could enable and later disable the screen from updating when a button is pressed:
Rule2
ON button1#state=3 do backlog power1 1; rule1 1 endon
ON button1#state=10 do backlog rule1 1; power1 1; delay 500; power1 0; rule1 0 endon
Configuring peripherals
There are a different set of supported peripherals out of the box depending on which Tasmota build you used. Refer to the BUILDS page at https://github.com/arendst/Tasmota/blob/development/BUILDS.md to determine if a particular feature is enabled. If it isn't, you will need to compile Tasmota with the desired feature enabled using the users_config_override.h file placed in the Tasmota source directory.
Setting up I2C
Some sensors and displays use the I2C protocol. The ESP8266 uses GPIO4 and GPIO5 as the I2C data and clock, respectively. When using I2C devices with Tasmota, configure the template as shown on the right. Save and activate the template. If configured properly, the i2cscan command should return a list of addresses that was found on the I2C bus.
CMD: i2cscan
MQT: tasmota/device/RESULT = {"I2CScan":"Device(s) found at 0x3c 0x40"}
SSD1306 display
The SSD1306 is an OLED display that comes in various sizes. These displays use I2C. The Wemos D1 OLED module is one such device with a screen size of 64x48. Tasmota supports this display through the tasmota-displays.bin image.
To get the display working:
- Attach the display to the Wemos D1 stack.
- Configure I2C for Tasmota (see section above)
- Run i2cscan via MQTT or the console. You should see the display at address
0x3c.
05:26:20.151 CMD: i2cscan
05:26:20.173 MQT: tasmota/D1-2/RESULT = {"I2CScan":"Device(s) found at 0x3c"}
- Configure the display in Tasmota by setting:
DisplayAddress 0x3c, the address discovered by i2cscanDisplayModel 2, for SSD1306DisplayWidth 64,DisplayHeight 48, for the display resolutionDisplayDimmer 100, to turn the display onDisplayMode 0, for text mode
- Save and restart (
Restart 1) - Confirm that text can be written by running:
Displaytext Hello.
To control the text location, specify any arguments within square brackets before the text when calling the DisplayText command. For example, to print "Hello World" across two lines, we write hello on line 1 column 1 (l1c1) and world on line 2 column 1 (l2c1):
Displaytext [l1c1]hello
Displaytext [l2c1]world!
There are many other parameters which can be found at: https://tasmota.github.io/docs/Displays/#displaytext-use. The most important ones you should know are listed below. You may chain any number of these together and they will run in the order they appear. Eg. [zl1c1f0s1]Hello would clear, then write the world Hello in the smallest font on line 1 column 1 after clearing the screen.
| Command/parameter | Result | Example |
|---|---|---|
| l# | line (1..) | l1 |
| c# | column (1..) | c1 |
| f# | font size (0..) | f0 |
| s# | font scaling (1..) | s1 |
| z | clears screen | |
| o / O | turns off / on the display |
With the power of Tasmota rules, we can trigger text to be written when a state changes. In the case of a CO2 monitor, we can create the following rule which clears and prints the PPM value on the first line of the display whenever the value changes.
Rule1 on MHZ19B#CarbonDioxide do DisplayText [zc1l1]%value%ppm endon
Rule1 1
This rule would print "400ppm" if the CO2 reading was at 400, for example.
For more information, see the rules section.
Compiling
Compile instructions are available at https://tasmota.github.io/docs/Compile-your-build/. The most simple way I've used is to use their docker image with the following commands:
$ git clone https://github.com/tasmota/docker-tasmota
$ cd docker-tasmota
$ docker build -t docker-tasmota .
$ git clone https://github.com/arendst/Tasmota.git
$ docker run -ti --rm -v $(pwd)/Tasmota:/tasmota -u $UID:$GID docker-tasmota -e tasmota
The different builds are available at https://github.com/arendst/Tasmota/blob/063611314777d4dd9dc8c25905f19f8b25f510aa/platformio.ini#L18
Project structure
Peripherals are prefixed in the source tree with xdrv (driver), xdsp (display), xlgt (lights), xnrg (energy), xsns (sensors).
Creating a new sensor driver
See: https://tasmota.github.io/docs/Sensor-API/
After creating the sensor driver file, edit the configurations header file and recompile: