I have used the official ESPHome container to flash some Sonoff TX switches. Initial flashing requires a USB to UART convertor. Next, the firmware can be changed / updated / upgraded over the air.

To flash the firmware, these are the basic steps:

• generate a configuration file
• put the main chip in serial bootloader mode
• flash the chip

Note: I am using podman. To use docker, replace podman with docker.

Preparation

Get the container:

podman pull docker.io/esphome/esphome:latest

Generate the configuration file

Normally you should read at least Getting Started with ESPHome to create a basic configuration that can be changed / updated / upgraded later.

This is a basic configuration generated using the wizard:

esphome:
  name: wizard_config
  platform: ESP8266
  board: esp01_1m

wifi:
  ssid: "Your_SSID"
  password: "Your_PASS"

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Startup Config Fallback Hotspot"
    password: "B3jelu0fjQZD"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:
  password: "Bk4JG6gtjlax"

ota:
  password: "Bk4JG6gtjlax"

At least, generate one for each device, replacing:

• the name wizard_config with a unique one for each device
• Your_SSID and Your_PASS with the ones you use

Serial bootloader mode

Warning: make sure the switch is not connected to the mains voltage ! Do not execute these procedures with the switch connected to the mains voltage, to any appliance or plugged in !

Remove the mainboard from the switch and observe the pins:

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To comunicate with the ESP8266, you need to connect the converter to J3.

To enter bootloader mode, ESP8266 and ESP32 must start with GPIO0 connected to Gnd. GPIO0 is marked on the back and a Gnd connection can be made from J1.

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• make the connections, no soldering is required if you bend the pins a little
• connect the USB to UART convertor to the PC. The board should start, you may see the signal LED blink
• disconnect the red wire
• with the green wire connect the pin marked GND on J1 with the GPIO0 (TP2) pin
• connect the red wire
• wait a few seconds and remove the green wire

Now the ESP8266 MCU should be in serial bootloader mode, the signal LED should NOT blink.

Flash the chip

Replacing wizard_config.yaml, execute:

podman run --rm -v "${PWD}":/config --net=host --device=/dev/ttyUSB0 -it esphome/esphome wizard_config.yaml run

The run command will execute these steps:

• validates the configuration
• compiles a firmware
• uploads the firmware (over OTA or USB)
• starts the log view

Or you can do it in steps:

# validate the configuration file
podman run --rm -v "${PWD}":/config -it esphome/esphome wizard_config.yaml config

# compile
podman run --rm -v "${PWD}":/config -it esphome/esphome wizard_config.yaml compile
# ...
# RAM:   [====      ]  43.5% (used 35620 bytes from 81920 bytes)
# Flash: [====      ]  38.4% (used 393308 bytes from 1023984 bytes)
# Building .pioenvs/wizard_config/firmware.bin

# upload with the USB to UART convertor
podman run --rm -v "${PWD}":/config --device=/dev/ttyUSB0 -it esphome/esphome wizard_config.yaml upload

# reset the board
# disconnect the red cable for a few seconds

# show logs from running node using the network connection 
podman run --rm -v "${PWD}":/config --net=host -it esphome/esphome wizard_config.yaml logs

# clean build files
podman run --rm -v "${PWD}":/config -it esphome/esphome wizard_config.yaml clean

More information

ESPHome:

• Getting Started with ESPHome
• Configuration Types
• Automations and Templates
• Frequently Asked Questions

ESPHome with Sonoff T3 EU 3 Gang

Serial bootloader details:

• ESP8266 Boot Mode Selection
• ESP32 Boot Mode Selection

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