DO NOT CONNECT THE SWITCH TO AC POWER AT ANY POINT THE CASE IS OPEN.

Bridge the Nano's GND and Reset pins.

The TX/RX pins don't need to be swapped.

Hold the button on the side, plug it into the computer, release the button after 5 seconds

sudo dmesg -w

/dev/ttyUSB0

Install the pyserial python module. Pip for most people, an AUR for Arch.

sudo pacman -S python-pyserial

Download the esptool to do the flashing

cd ~/Downloads && git clone https://github.com/espressif/esptool.git esp && cd esp

Download the tasmota firmware

wget http://ota.tasmota.com/tasmota/release/tasmota.bin

Check if your computer can talk to the ESP

sudo python3 esptool.py --port /dev/ttyUSB0 -c esp8266 flash_id

Anything other than this output means your wiring is wrong, or you didn't put it into programming mode (the button holding part)

Actually write the firmware.

sudo python3 esptool.py --port /dev/ttyUSB0 -c esp8266 write_flash 0x0  ~/Downloads/esp/tasmota.bin

After it's done, connect to the new tasmota wifi network and go to this address.

https://192.168.4.1/

• Go to your router and set a DHCP reservation.

• Go to Configuration -> Configure Module -> Module type

  • Change the module to "Sonoff S31 (41)"

• Go to Configuration -> Configure Other

  • Change the Device Name and Friendly Name 1 to something else

  • "Sonoff-S31-A"

• Go to Configuration -> Configure MQTT

  • Input the settings that match your broker options in home assistant

Optional:

• Login to your Home Assistant server and go to Settings > Add-Ons and click the Add-on Store button.

• Search for “TasmoAdmin” in the search and then click on the “TasmoAdmin” add-on in search results.

• In the add-on configuration disable SSL or it wont start.