ESP32/8266/12E implementation of Unifon digital domfon/intercom

NO

Witam, chyba nigdy

I think never. It is hobby project :)

I'll share my learnings here.

• L+ is analog, 0-11V
• L- is GND
• digital domofon - it is only the name. It is still analog in practice.

ESP works only on 3.3v. Intercom is working on 11v. Some resistors is needed. My setup:

---
title: Connection diagram
---
flowchart TB
    eGND[GND]
    iGND[L-]
    iLP[L+]
    eD1[D1]
    R1[Resistor 10kΩ]
    R2[Resistor 3.5KΩ]
    
    eGND<-->iGND
    R1<-->iLP
    R1<-->eD1
    eGND<-->R2
    R2<-->eD1
    
    subgraph Intercom
        iGND
        iLP
    end
    
    subgraph Wires
        R1
        R2
    end
    
    subgraph ESP8266
        eGND
        eD1
    end

In IDLE mode, L+ is low state

In dialling mode L+ starting be UP. And then we have 58ms to count all Edge falling. Count of edge falling is dialled number.

After 58ms of dialling, the event type need to be detected.

• ringing: 500uS interval
• wrong gate pin: 280uS interval, 530uS cycle
• correct gate pin: 218uS interval , 424uS cycle

Solution implemented: Wait after dialling for next pull-up, start counting pull-ups for 10ms.

• 10 ±1 = calling
• 5 ±1 = wrong gate ping
• 23 ±1 - correct pin

Cancelling signal (call & press (C) Key) looks like 10ms UP state, and then failing to 50% of signal.

• after pickup the intercom, detected signal how call is ended
• after pickup the intercom, detected opening the gate signal.
• detect how procedure of wrong pin & correct pin is ended.
• detect how to pickup the call.

• implement two way voice communication
• find some ADC/DAC working with 10 voltage or any other solution