EPS32 Smart Intercom Extension

ESP32 based pcb for controlling a Siedle HT611-01 Intercom

This is a project I did with the my fellow T3chGuyz. Its a pcb (printed circut board) that controls an existing intercom device installed in a multi family home. Similar to the Nuki Opener. Can also be used for other devices meeting some requirements.

Features

• Open the main door
• A sensor for the doorbell
• Mute the doorbell
• Ring to open

Getting Started

Warning: I am by no means an expert. Do this at your own risk!

If you want to use this project, you will need a few steps:

Prequsitions:

• Soldering equipment suitable for soldering smd components (iron, tin, flux, tweezers, etc.)
• Some jumper wires and clamps (depending on the device it will be installed in)
• Some $$$ (not much I promise)

Ordering: In order to start building the pcb, you have to order all parts and the pcb itself.

Ordering the parts: This is pretty easy. There is a BOM (bill of meterials) csv file for every revision in the github releases section. Just use your favorite supplier and import it. I have used LCSC. Thus the BOM also contains a LSCS part number for every part.

Use the exact same parts, or similar ones if they are out of stock. Just make sure to use the correct value and package. For most smd parts its 1206 but make sure to match it in the BOM. If you have found all parts then order online. For me this was around 5$ in 2024 (you may have to order more parts then needed depending on the supplier).

Ordering the pcb: This is a little more tricky.

• From the same github release download the Gerber File zip archive.
• Import it at your favorite pcb manufacturer. I used JLCPCB.
• Change the color to your desire but keep most settings default. Make sure to Order just the pcb (if you dont want to let it be assembled)
• Place your order and thats it. You may have to order more than 1 pcb, depending on your manufacturer. This was around 2$ for me in 2024.

Now you wait for all the parts to arrive. The right time to buy some flux. (Trust me you will need it :))

Assembling Once all your parts have arrived you can start to assemble your device.

This is pretty straigt forward. If you have never soldered smd components, I recommend you watch a tutorial first. You you are german I can recommend this one

Make sure to use the correct parts based on their qualifier. Use the pcb layout picture for help

Function Testing Of courese use a multimeter to test if all connections are made as in the layout.

Additionally, test the USB connection. This is pretty hard to get right at the first attempt. What I did:

• plug in a USB-A to USB-C cable

• use a multimeter to test connection from the exposed data and power pins in the USB-A port

• Make sure D+ and D- are NOT connected

• Make sure USB power is connected to D4

• Once thats good, plug in power and see if D4 outputs around 5V and U3 outputs around 3.3V

• If thats done youre ready to go

Installing the firmware I used ESPHome to flash this device. The yaml config can be found in this repo too.

To get started with EPSHome see their website.

Make sure to adapt your WiFi credentials and add a esphome api key. I recommend to setup a new device in ESPHome and then copy the yaml contents in there.

The pins should match, but you can double check with the schematic.

Installation

For installation in a Siedle HT611-01 just connect the labeld pins to the same labels on the PCB.

1. Remove the cable that connects LW on the intercom to the bell
2. Use a clamp and connect it to the LW_IN on this device
3. Connect LW_OUT on this device to the plus on the doorbell
4. Connect C on this device to the bell minus
5. Keep the connection from bell minus to the intercom
6. Connect 6.1 on this device to 6.1 on the intercom
7. Connect I on this device to I on on the intercom
8. Connect 5V to a power supply
9. Connect GND to a ground

Alternatively you may run it via USB-C

Explaination

• 6.1 - Door Opener plus

• I - Door Opener minus

• LW_IN - "Leutwerk" in

• LW_OUT - "Leutwerk" out

• C - "Leutwerk" minus

• 5V - connect some 5V power supply. Can be a cut up usb cable

• GND - connect ground

• DON'T connect 5V and usb at the same tme. D4 is a safety machanism for that but I cannot garantuee anything.

How it Works

The functionality is pretty simple. Mostly relais.

• Opening the door is handled by the first relay, that will just simulate that the button is pressed. Pretty simple
• Muting the doorbell is also just a relay, but connected to NC. So your doorbell will ring if the device is turned off
• The doorbell sensor uses an optocouppler to get a notice of the AC signal from the intercom
• The rest is standard stuff for a esp32. The boot and en button, voltage regulation, etc. is pretty similar to a ESP32 dev board

Everything connected to the intercom is a separate circut, meaning no direct connection from the ESP32 to the intercom itself.

Hardware requirements

If you want to install this in another intercom, make sure to meet these requirements:

• door opener circut co connect to
• Ring circut to connect to
• MAX 2A on the Ring circut (requirement by trace width)
• MAX voltage for opening and bell muting is 250V since I used overdimensionized relays. May change in a later revision.
• The circut for reading the bell signal is made to read a 12V AC signal. May work with DC, havn't tested