🏠 Smart Intercom with ESP32‑C6 and Thread

An ESPHome project that turns a regular analog intercom into a Home Assistant‑controlled smart device.

🇷🇺 Русская версия

✨ Features

• Incoming call detection via an optocoupler (GPIO3 with pull‑up).

• Two switching optocouplers:

  • «Standby» mode (GPIO1) – simulates the handset resting on the hook.
  • «Answer / Door open» (GPIO4) – simulates picking up the handset and pressing the door‑open button.

• Four operation modes selectable from Home Assistant:

  • Off – fully manual control.
  • Once – answer and open the door on the next call, then switch to Off.
  • Always open – automatically answer and open the door on every call.
  • Reject – always drop the incoming call.

• Manual buttons in the HA interface to open the door or reject a call.

• Adjustable timing parameters for different intercom models.

• Thread support (OpenThread) and IPv6 – ready for Matter.

• OTA updates and encrypted API.

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📦 Hardware Requirements

Component	Purpose
ESP32‑C6 DevKitC‑1	Wi‑Fi 6, Bluetooth 5, Thread controller.
KAQY212S optocoupler	Solid‑state relays (normally open) for galvanic isolation.
220Ω resistors	Current limiting for the optocoupler LEDs (depends on GPIO voltage).
5 V power supply	Powers the ESP32‑C6.

💡 Why KAQY212S?
This chip contains a bidirectional MOSFET switch, rated up to 60 V / 400 mA, making it perfect for analog intercom signals (both AC and DC). Full galvanic isolation eliminates noise and protects the ESP.

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🔌 Wiring Diagram

The ESPHome configuration uses the following GPIO pins (customizable in the substitutions section):

ESP32‑C6 GPIO	Function	Connection
GPIO1	«Standby» optocoupler control	LED anode → resistor (220–470 Ω) → GPIO1, LED cathode → GND. Output pins (4 & 6) in parallel with the handset hook.
GPIO3	Call detection input	Optocoupler output pins (4 & 6) in parallel with the call buzzer. The optocoupler LED is driven by the call signal through a resistor. GPIO3 has internal INPUT_PULLUP.
GPIO4	«Answer» optocoupler control	LED anode → resistor → GPIO4, LED cathode → GND. Output pins (4 & 6) in parallel with the door‑open button / answer contact.

Output Logic

• «Standby» optocoupler (GPIO1) – Normally ON (output.turn_on), its contacts are closed (handset on hook). It briefly turns OFF during answer or reject.
• «Answer» optocoupler (GPIO4) – Normally OFF. Turns ON to simulate lifting the handset or pressing the door‑open button.

Call Detection

The third optocoupler is wired across the call buzzer line. When a call signal (AC or DC voltage) appears, the LED lights up, closing the output contacts and pulling GPIO3 to GND. The firmware uses inverted: True, so a closed contact is treated as a press (on_press).

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🏡 Home Assistant Integration

The following entities will be created in HA:

• Select «Mode» – switch between automation modes.
• Binary Sensor «Incoming call» – indicates an active call.
• Buttons «Open door» and Reject» – manual triggers.

All controls are available on the ESPHome device card.

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⚙️ Timing Parameters

Adjust the values in the substitutions section to match your intercom:

Parameter	Default	Description
call_end_detect_delay	3000ms	Minimum call pulse duration for reliable detection.
before_answer_delay	10ms	Delay before starting the answer sequence (allows line stabilization).
answer_on_time	1500ms	Duration the handset is «lifted».
open_on_time	600ms	Duration of the door‑open button press.
after_open_delay	500ms	Extra pause after opening before returning to standby.

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🐞 Troubleshooting

• Call not detected:
  • Ensure inverted: True is set for GPIO3 (active low).
• Door does not open:
  • Increase open_on_time (e.g., to 800ms).
  • Check with a multimeter that the «Answer» optocoupler actually closes the button contacts.
• Modes switch but automation does not trigger:
  • Enable ESPHome logs and confirm that incoming_call changes to on during a call.
  • Verify the selected mode matches the expected behavior (especially «Once»).

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🧵 Thread & IPv6

The device is configured as a Full Thread Device (FTD) and will attempt to join an existing Thread network using the TLV from secrets.yaml.

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📸 Screenshots

📄 License

MIT © 2026 [F-Lab] Made with ❤️ by f1x6r