I would like to communicate with a Raspberry Pi in my home through Zigbee, so I can connect an OpenTherm gateway and use it as a Zigbee OpenTherm thermostat.
The Pi is not the hardware that runs my HA, it would be an endpoint in this configuration.
Is that even possible? If so, how?
The Zigbee coordinator that I use on my HA instance is the Sonoff USB Dongle Plus, the Pi is a 3b+ which has a Popp ZbShield Zigbee dongle that connects directly to the GPIO.
Nobody’s developed such a thing as far as I know
I was afraid so. I couldn’t find anything about it, except a very old post somewhere with a similar question.
Naively, you’d think it should not be too hard, the dongle can send and receive messages, all that needs to be done is to tell it not to try and be the boss. But most likely it is more complex than I think.
People have done something similar with a Sonoff ZBbridge device, turning it from a wifi-connected coordinator into a repeater. That device uses the same EFR32MG21 chip as my ZbShield. So it looks like it could be done.
You could connect a zigbee board to the rpi via a serial (uart) connection. Develop some code to correspond. Maybe.
The zb shield is already connected through the UART serial, so that part is easy. The software development is more of a time investment than I am willing to make for this.
I think I will get the manufacturer’s thermostat with my new boiler, and put an otgw in between. That gives me a safe backup plus space to tinker.