Wi-Fi Doorbell

IOT (The internet of things)
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Alrighty. Like in every other house that was built decades ago, the original doorbell arrangement has stopped working and I have absolutely no idea how to get a cable between some point in the house and the new border post (as of around 1996 according to house plans), as was mandated by a fortification of the security measures against unlawful immigration.

So for a really long time, we’ve just been running with these. Two of them, one for the main house and one for the business operating from the backyard.

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All good and well, except those darn transmitters either stop working or they get stolen. I have no idea why they get stolen, but they do. So by now I have several of the items on the left, and only one working one of the items on the right. So I bought a few toys from a hobbyist place, applied some lazy engineering (a real engineer would do this at a quarter of the cost no doubt), and now I have a Wi-Fi enabled doorbell.

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doorbell
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The mp3-player board can play up to 7 different sounds, which means this can be more than a doorbell. It can notify you of other things too.

I also acquired a Sonoff RF-bridge, and two 433Mhz doorbell buttons that will go next to the gate (suitably locked down).

Total overkill, yes. But a lot of fun.

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What doorbell button did you end up buying?

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My driveway is so steep that most visitors spin their wheels at the bottom. That is how we know we have visitors and no door bell needed as the visitors all bring their own tyres to spin :smiley:

But I like your solution.

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The Eachen 433Mhz one. Looks like this:

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I’m going to mount two of them inside an electrical box with a clear cover. Then I’m going to drill holes large enough to get a finger through to push the button, but not so large that the button can be stolen without a screwdriver. I’m betting on the average street scavenger either not carrying tools, or not wanting to spend the time…

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And just in case people are interested.

The Wi-Fi side is an ESP8266 in the form of a Wemos D1 mini. The MP3 player is from Micro robotics. Of course you can use any similar device.

The MP3 player acts like a USB mass storage device. You upload MP3s named like 001.mp3, 002.mp3, etc. The device has 7 pins, which when pulled low plays the corresponding mp3.

Of course it can do way more than 7 through its serial interface, but I opted to simply connect 4 of the GPIOs to the first 4 pins on that playter. Which, btw, is numbered incorrectly. Number 1 is right at the top, and 2, 3 and 4 goes from the bottom upwards.

The device comes pre-programmed from the factory, counting from 1 to 7 in Mandarin.

It also has an onboard amplifier good for up to 3W (into a 4Ω speaker), but I wired it to the existing 8Ω speaker and it is plenty loud.

The ESP8266 is then configured to hold its GPIOs high, and I can pull the pins low to signal some kind of condition and play the corresponding sound. The only downside: When turning the device on the very first time, the pins start in the low state for a microsecond, and it triggers the device. After that it is fine.

The mp3 player sits in a socket so it can be easily removed to upload new sound samples.

Unfortunately it needs a 5V supply. So it needs to be plugged in somewhere.

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Total costs?

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Boring… :rofl:

Should be bit banging the sound directly from the D1:

https://github.com/earlephilhower/ESP8266Audio#software-i2s-delta-sigma-dac-ie-playing-music-with-a-single-transistor-and-speaker

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Too much. I already had the D1 mini, but if I had to buy one it would be around R120. The MP3 player is around R100. The enclosure and speaker is free since I already had it. The USB cable and power supply that powers it… free cause there’s always one from an old phone around. A bit of stripboard… I would have to add the cost of that, but I already had some.

So around R220 for the receiver. And I intend building two.

The 433Mhz buttons were R170 a piece. The plastic case they go in to prevent theft was R160. The Sonoff RF bridge is around R300 (but that will be used for more sensors and stuff in the future too, so lets ignore that).

So total cost of just the doorbell part is R440+R340+R160 ~= just under a thousand. For that price I could have bought 5 new DigiTech wireless doorbells :slight_smile:

But, there is a larger part of the project. Recently I also acquired a couple Askari security beams. I have the alarm interface wired to another Sonoff device, a NodeMCU this time, because it includes a voltage regulator onboard and the Askari interface requires 12V. This sends presence notifications to HomeAssistant whenever the beam picks up movement. Let’s rather not count the cost of this part, since that Askari thing alone is quite costly.

The doorbells will double as beam monitors. Automation means I can automate when audible notifications should be sent, and when it shouldn’t. The hair salon next door, where there is often a lady alone after hours, gets the same benefit from the “doorbell” that is fitted there.

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Many play a round or 2 of golf for that and have nothing but the “Pain and Heartache” that goes with it…

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My old intercom stopped working a year ago as well, so I found an opened Digitech wireless doorbell in Builders around the same time on the discount table. Bought it for like R80 or something. Tested it and turns out the Sonoff RF Bridge picks up these 433Mhz doorbell signals!

So my wireless doorbell is now the Digitech transmitter, sending to the RF bridge, goes into Home Assistant and as soon as the button is pressed, it
a) takes a snapshot from the nearest camera
b) sends the notification to my phone with the pic and “Doorbell!”
c) Announces “Western doorbell” (I have two gates, Eastern and Western) over the Google Home.

The latter is particularly useful because our dog learned the sound of the intercom and would start barking instantly when it rang, often waking the baby. But somehow the cool calm voice of Google Home never bothers her.

Problems:

  1. The range is terrible. I have to keep the RF Bridge in a window with LOS for the signal to reach it reliably
  2. Doesn’t help if they steal the Digitech button as @plonkster indicated.
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Did you need to make any modifications, or does it work with the stock firmware? Specifically, there are two MCUs in the bridge, one is the ESP8266 doing the Wi-Fi, and the other is some other chip doing the other side. I’ve read that you can flash the RF side with something called Portisch which then allows you to gain access to the raw RF (as long as it is 433Mhz). You didn’t have to do any of that?

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Nope, just flashed Tasmota on it.

The Tasmota console shows this when ever an RF signal is received:

12:52:57 MQT: tele/RF_Bridge/RESULT = {"RfReceived":{"Sync":12500,"Low":420,"High":1210,"Data":"E20FDE","RfKey":"None"}}
12:54:16 MQT: tele/RF_Bridge/STATE = {"Time":"2021-05-15T12:54:16","Uptime":"90T18:54:41","Vcc":3.186,"Wifi":{"AP":1,"SSId":"Mozart2.4","BSSId":"74:AC:B9:B4:36:37","Channel":6,"RSSI":100}}
12:58:09 MQT: tele/RF_Bridge/RESULT = {"RfReceived":{"Sync":12510,"Low":420,"High":1210,"Data":"E20FDE","RfKey":"None"}}
12:59:17 MQT: tele/RF_Bridge/STATE = {"Time":"2021-05-15T12:59:16","Uptime":"90T18:59:41","Vcc":3.186,"Wifi":{"AP":1,"SSId":"Mozart2.4","BSSId":"74:AC:B9:B4:36:37","Channel":6,"RSSI":100}}
13:02:00 MQT: tele/RF_Bridge/UPTIME = {"Time":"2021-05-15T13:02:00","Uptime":"90T19:02:25"}

(in this case the “Data”:“E20FDE” is the code sent by a Sonoff RF PIR, but the same concept applies when receiving a signal from the doorbell).

You can also use it to send any other signal, so would be quite easy to wardrive around and trigger people’s doorbells.

This is also the reason why I wouldn’t ever use these basic RF-based 433Mhz sensors for a serious security system.

EDIT: AFAIK the standard firmware should also work – you just put it into learning mode with eWeLink and code a signal into it. But I don’t really like eWeLink.

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Well now I am thinking more of triggering my own doorbell(s)… :slight_smile:

The receiver end learns. The first code it receives after installing the batteries is what it uses. So in theory, you just need to send an acceptable code and the DigiTech units should accept it…

I still have another two of those units. Maybe later I will try something,

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OK, playing around a bit. The random transmitter/receiver I bought off BoB years ago actually works with the RF bridge. The doorbell transmitter doesn’t seem to work.

433mhz
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Edit: I note that some of the devices have a PT4302-X chip in the back, and from the chosen crystal I can see it’s set for 433Mhz. Some of the others have a little H3V4F board soldered on. So it seems there are at least two variants.

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Interesting findings! Do you mean the Eachen one doesn’t, or the one marked “Salon”?

I had that Digitech go dead on me too, only to discover it was practically full of water. Drained it, dried it and good as new.

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The one marked “Salon” does not send something that is recognisable by the RF bridge.

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Gaaah. The first thing you should do with these things is test the range. Not like me, who finishes the entire build and THEN finds out the range is lacking. I managed to get it working by moving the RF bridge closer.

At 20 meters it worked, but it wasn’t dependable. The nearest plug point I had was 12 meters away, and that seems to work consistently.

If I redo this in the future, I’d skip the 433Mhz part and just make a plan to extend my Wi-Fi range so the button connect directly to a Wi-Fi enabled module.

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Would be interesting to test if the original doorbell receiver worked further away.

No idea if one can give the RF bridge a bigger range? I had to place mine in quite a number of different spots before it could pick up a door sensor, motion sensor, the doorbell button and the Sonoff remote that i use to trigger various things in the house.

(The remote used to have two buttons allocated to opening my driveway gates, before I realised the security risk)

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Oh it did. It worked at least up to 20 meters without an issue. The Sonoff RF bridge has easily only half the range.

There is a guy on the homeassistant forum (I think?) that attached an external antenna and got it up to 50 meters.

Yup, it’s actually kinda scary. Similarly, I discovered decently that the little ET keycode panel my security company installed… still had the default master code on it. Any idiot who knew what to do could just walk past and make himself a user… the only way to be sure they didn’t is to clear the entire thing :frowning: