Sonoff S20 and espeasy

Flash espeasy

Image can be found here.
To boot the sonoff into flash mode, press and hold the button while connecting it to power.

./ --port /dev/ttyUSB0 write_flash 0x000 ESPEasy_R120_1024.bin -fs 8m

Connect to wifi and configure

Connect to ESP_0 with password configesp and set up the wifi connection.

After connecting to wifi open the webinterface http://ip.of.sonoff/config and configure the name and unit number. The name of my sonoff is sonoff-s20.

Configure Hardware and Devices.

espeasy-hardware espeasy-button espeasy-relay

Enable rules: Tools – Advanced – Rules: Checked

Now there is a new menu entry named Rules

On Button#State=1 do
  if [Relay#State]=0

Now you can toggle the relay with the button.

MQTT usage

I use the protocol OpenHAB MQTT. So I can subscribe these events:

# mosquitto_sub -h my.mqtt.server -t "#" -v
/sonoff-s20/Relay/State 1
/sonoff-s20/Relay/State 0

To switch on and off you can publish these messages:

# mosquitto_pub -h -t "/sonoff-s20/gpio/12" -m "1"
# mosquitto_pub -h -t "/sonoff-s20/gpio/12" -m "0"

It is also possible to change „Relay“ to „gpio“ and „State“ to „12“. In this case, the subscribed and published strings are the same, but the rules also have to be modified. is the IP-Address of the MQTT-Server (for example, mosquitto).

openHAB configuration

After configuration of the mqtt-binding in openhab.cfg I created a new item-file

Switch sonoff01 "Sonoff Socket" {mqtt=">[mosquitto:/sonoff-s20/gpio/12:command:ON:1],>[mosquitto:/sonoff-s20/gpio/12:command:OFF:0],<[mosquitto:/sonoff-s20/Relay/State:state:MAP(]", autoupdate="false"}

I also created the file transforms/


5 Gedanken zu „Sonoff S20 and espeasy

  1. Răzvan T. Coloja

    Very thorough tutorial. I used it to successfully install the firmware on my S20. i have one question though: how do I use MQTT? Where do I input the following lines?

    # mosquitto_sub -h my.mqtt.server -t "#" -v
    /sonoff-s20/Relay/State 1
    /sonoff-s20/Relay/State 0


    # mosquitto_pub -h -t "/sonoff-s20/gpio/12" -m "1"
    # mosquitto_pub -h -t "/sonoff-s20/gpio/12" -m "0"

    Do i need a module soldered on the board for them to work or do they work out of the box? In other words – how do I control the plug after installing the firmware?

  2. Răzvan T. Coloja

    Hi Micha

    I know they are Linux commands. My question is do I input them in the OpenHAB console or directly into BASH? Does OpenHAB need to run on my laptop for them to work? Should I try

    mosquitto_sub -h -t "#" -v /sonoff-s20/Relay/State 1

    or do I make a bash script like this:

    mosquitto_sub -h -t "#" -v
    /sonoff-s20/Relay/State 1
    /sonoff-s20/Relay/State 0

    (where is my plug’s static IP address).

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