Nest Hello doorbell - detect button press via relay

Hi, we are currently in the process of building a new house and I am deciding on what doorbell to use, since we use Google Home I would like to use Nest Hello aswell, since Ring can’t be integrated with it.
I know that through Nest component I can get the binary sensors to detect motion, but as I understand there is no way to detect the button press, which is most important (for example to turn on lights after 10sec when nobody is home and it is night).

I know that using the Nest Hello puck connected to the chime it is possible to make it ring, but my question is using this feature if I connected a relay instead of a chime, then connect the output switch pins of the relay to the input pins of Raspberry Pi where HA runs, would it be possible to detect this in the HA? Or if the relay is far from the RPi, I think it should be possible to use something like ESP8266 and send HTTP requests to HA via Wifi.

I have read somewhere that inside of the puck there is a Opto MOSFET, so maybe it would be even possible to get something more useful (on digital voltage levels) out of it to even skip the clicky relay.

Have anyone tried anything like this? Or would it even work?

I have a nest Hello but also connected a binary z wave sensor connected to the chime. In this case I used a normal Fibaro door/window sensor which also has a binary input, was more convenient as it uses a battery instead of separate power. I still have a normal ‘old fashioned’ chime (the same as I had before I had the nest Hello).

So in short: Get a relay that switches when power comes to the chime (eg someone pressed the button), the other pins of the relay are connected to the binary z wave sensor which is integrated in HASS. If you don’t like zwave there are probably many other sensor you could use.

I already had this setup before I had the Nest Hello and always worked perfect and kept working after installing Nest Hello.

Thanks for the answer :slight_smile: the z wave sensor seems like a good idea, I will have to look it up. I almost forgot about some z wave gateway integration in my HA, but I reckon that I will have more z wave compatible stuff (for example those actual door sensors) in the future, so this will be the easiest method how to get the signal to HA.

I always hate, when I have to decide which smart device to get, that they are so closed with their abilities, which is totally unsuitable for some power users as I like to tinker with stuff… I wish all of them had some open APIs.

Could you detail your setup with this a little or send some screenshots?

Are you referring to the automations in HASS or the hardware part?

The hardware part if possible. I’ve been looking at the Fibaro Smart Implant and I am thinking there may be a way to use that as an alternative.

I think overall setup depends a bit on how your doorbell is setup currently. I have a 24v AC trafo and a traditional chime. The doorbell pushbutton simply connects the circuit so the chime ‘rings’ . Like the schematic here. The fact that I also now have a Nest Hello connected does not change that setup in the basis; most people have their doorbell wired like the schematic above so Nest Hello allows for a similar setup (ca be found in nest Hello installation manual).

Now the issue is that you cannot just connect a (binary) sensor in between the existing wiring as this would mean that when someone presses the doorbell 24v AC would rund through the binary sensor and it would blow up…

So you need to connect a relay (something like this but many relays will work). Connect two parallel wires to the chime (so the two that go to the chime) and run them to two pins of the relay. Then connect two wires to the other pins of the relay (most relays have a different pin layout but it always says the layout on the relay itself) these pins go to the binary sensor. These pins will not have any current on them. The relay takes care of that.

I used a simple Fibaro doosensor Gen 1 that also has a binary input and get’s it’s power from a battery (lasting a year or so). I’m sure you can also do it whit the Fibaro implant but don’t forget that the implant also needs power so you will have to have some kind of power supply (according to specs 9-30 DC) at that location.

If you use google translate you can see a similar project here.