The most important part of the adapter (besides the physical eBUS isolation) is the firmware for the ESP32-C3.

The easiest way of flashing the firmware is by using a web browser supporting Web Serial.

Alternatively, esptool and friends can be used as well, but this is much more complicated and not explained further.

Flashing via web browser

The following steps need to be carried out for flashing the firmware by using a web browser supporting Web Serial:

  1. connect the adapter via USB and keep the button pressed while doing so (force bootloader mode)
  2. pick the desired version and click on "CONNECT":
    Select one of the options above first!
    Installer powered by ESP Web Tools.
  3. pick the serial Port "USB/JTAG serial debug unit (COM...)" and click on "Connect" (e.g. on Windows)
  4. click on "INSTALL ..." and follow further instructions

If the adapter was flashed for the first time, the power supply (USB) must be briefly disconnected in order to exit bootloader mode. If you want to make the WIFI settings right away, the connection of the flash tool must also be renewed, i.e. exit the dialog completely and re-establish the connection via “CONNECT”.

In case the dialog does not show options for configuring the network (“CONNECT TO NETWORK” or similar), it might be necessary to wait 10 seconds, go to “LOGS & CONSOLE”, and click on “BACK” there, in order to get the communcation ready.

The connection to your own WIFI or Ethernet can be established via the dialog via “CONNECT TO NETWORK”. Available networks are scanned and offered for selection, including Ethernet in case an USR-ES1 or W5500 module is plugged in (appears as “#ETHERNET (via USR/W5500)” in the list). If the connection works after entering the optional password, the access data is also saved.

Afterwards the website of the adapter is shown by using the entry “VISIT DEVICE”. Alternatively the easi> Interface is available for configuration via “LOGS & CONSOLE”.

After initial flashing and also by pressing the button during boot, the firmware starts a WIFI access point with SSID “EBUS” without a password. When connecting to that one, the most important settings can be adjusted on the page


The easiest way of configuration is via network, e.g. by using the WIFI access point with SSID “EBUS” (without a password), that is started after initial flashing or when pressing+holding the button during boot (while the LEDs fade).

Alternatively the easi> interface can be used via serial connection as well. This is possible directly through the firmware page as explained above, or via putty, minicom or any other terminal software allowing to connect to the serial USB port. Then the easi> interface of the adapter appears that offers many commands for configuration and testing. Using the “help” command reveals them including the parameters.

When using Ethernet, it is recommended to use the steps described above for initial setup, as the Ethernet interface needs to be configured first.