Manual · for version 1.4.6 · View on GitHub

This manual comes from the public repository of the Home Assistant integration. It still uses the old name OpenThermostat, and calls the box the E32: the BBQKees Gateway E32 V2 that Emthera runs on today.

USB installation, backup and recovery #

The firmware and the project's main repository are not public at the moment. What these guides say about downloading the firmware or a release ZIP from GitHub, updating the E32's firmware from Home Assistant or with Check for updates, and the tester program's GitHub form does not work for now. The Home Assistant integration is installed and updated through the Marketplace as described. A few references to pages that are not public have no link here. Questions or problems: open an issue.

Installing OpenThermostat for the first time? Follow the installation guide. It covers downloading the release, flashing e32v2-factory.bin over USB, the first start and everything after it.

This page covers the less common USB tasks: a full backup before the first installation, a clean reinstall, and going back to the original firmware.

Task	Where
First installation on a new E32 V2	Installation guide, section 2
Normal firmware update (keeps settings)	Installation guide, section 9
Forgotten web password (`password-reset`)	Installation guide, section 10
New router or Wi-Fi password (`setup`)	Installation guide, section 10
Full backup before the first installation	Below
Clean reinstall (erases all settings)	Below
Back to the original EMS-ESP firmware	Below

The steps below use the browser tool ESPConnect in Chrome or Edge, as in the installation guide. ESPConnect is made by an independent developer. esptool can do the same; see the hardware guide for its backup commands.

Make a full backup first #

A BBQKees E32 V2 usually comes with EMS-ESP. Installing OpenThermostat erases it. Make this backup if you may want to go back.

In the EMS-ESP web interface, download its settings (Settings → Upload/Download; the wording may differ between EMS-ESP versions), and take a screenshot of its system information (version and board profile).
Disconnect the E32 from the boiler and any other power supply, and connect its USB-C port to your computer.
Open ESPConnect, connect at 115200 baud and check Device Info: an ESP32 with 16 MB flash. In the security information, Flash Encryption and Secure Boot must be off. If they are on, or you cannot tell, stop: a raw backup may not be restorable.
Go to Flash Tools → Flash Backup & Erase. Enter start offset 0x0 and length 0x1000000 (the full 16 MB). Click Download Flash Region and save the file as e32-backup-a.bin. This takes a while; keep the computer awake and the cable connected.
Read it a second time with the same values and save it as e32-backup-b.bin. Do not copy the first file.
Both files must be exactly 16,777,216 bytes and identical. On Windows, open PowerShell in that folder and run:
```
Get-FileHash .\e32-backup-a.bin, .\e32-backup-b.bin -Algorithm SHA256
```
On macOS use shasum -a 256 e32-backup-a.bin e32-backup-b.bin, on Linux sha256sum e32-backup-a.bin e32-backup-b.bin. The two hashes must be the same.

Keep a copy somewhere other than this computer. A backup can contain your Wi-Fi and other passwords: never upload it to GitHub or share it.

Clean reinstall #

Flashing e32v2-factory.bin again gives a factory-fresh E32: Wi-Fi, password, rooms, paired sensors and all other settings are erased. Use it only when an ordinary update or the USB commands cannot help. Follow section 2 of the installation guide and then continue with the first start. If Home Assistant was connected, use Configure → E32 connection again afterwards.

Go back to the original firmware #

You need a complete, verified backup of this same E32 (see above), or BBQKees' official EMS-ESP recovery route.

Disconnect the E32 from the boiler and connect it to ESPConnect over USB.
Go to Flash Tools → Flash Firmware, select e32-backup-a.bin, set the offset to 0x0, tick Erase entire flash before writing and flash.
Before restarting, read the full 16 MB back (start 0x0, length 0x1000000) into a new file such as e32-restore-a.bin, without overwriting the backups. Its SHA-256 must equal that of the backup.
Restart and check the EMS-ESP web interface, its settings, board profile and network.

Without a working backup, reinstall EMS-ESP as BBQKees describes in its firmware update and downgrade guide and import the settings you downloaded in step 1 of the backup.

Check the EMS-ESP settings before you connect the E32 to the boiler again: a restored backup also restores EMS-ESP's own settings for sending on the bus.

If the USB connection fails #

Use a USB-C cable that carries data, plug it in fully and connect directly to the computer.
Close other programs and browser tabs that use the same serial port.
If no port appears, install the USB driver BBQKees recommends for the gateway.
If the tool still cannot connect, follow BBQKees' instructions for starting the board in download mode. Do not bridge pins on the board.

More technical background: E32 V2 hardware, backup and recovery.