ESPurna is a library of open/community sourced firmware built on arduino that can be used in place of the MppDevices.
The support structure for the library is quite useful with a web server used to configure the devices and a REST API that makes it relatively easy to integrate with AutomationManager.
The one drawback to this library is that it does not have http level event notification of changes, so external changes to the devices are not noticed by AM until the next refresh/poll period. The delay is typically < 30s and on average will be around 15s.
To get started, visit https://github.com/xoseperez/espurna/releases/ to see if there is a binary for the device and sensor you would like to use. Most of the ITEAD/sonoff devices can be flashed with new firmware (which is probably much safer than using their default implementations).
To burn your device, you need to connect it to your USB (the first time) and put it into flash mode. Following the first (successful) flash you should be able to use the over the air (OTA) support.
Flashing instructions are here: https://github.com/xoseperez/espurna/wiki/Binaries. I've added a few tips here to make it easier.
To use the device with AutomationManager
You'll need the web admin password that you used in the previous setup steps. AM will not retain the password, but it will find the device and use the assigned HTTP API key. You will need to repeat these steps if you change the key. In the device's web adming be sure to have enabled the HTTP API and, to use AUTO discovery, Alexa.
Alternative: Setup over Wifi
Troubleshooting
Device not available on your wifi network?
Retry the network setup. If the device's AP is visible, use the alternative wifi setup.
Web page does not appear
Restart your browser and use the url based password entry (see above).
Unauthorized
Double check the password. User is "admin".
With a web browser try entering the url based password as above.
When discovering with AM note some autofill entry fields add a space at the end.
Device does not start
Try booting with a serial port connected at 76800bps to see the boot messages. If you see a checksum error the flash didn't work. Try different parameters, DOUT will often work better than QIO or DIO. Note that the espressif flash utility will not allow you to select an alternate burn method and will reset it when it syncs with the chip for flashing. The default will not always work in that device. Try alternate flash settings with ESP8266Flasher.exe.