External control device for Edifier MR4 studio monitors that connects to the stock encoder button and the status LEDs via optocouplers, simulating button presses and reading the LED states with full galvanic isolation. Enables seamless integration with Home Assistant.
- Complete Galvanic Isolation – both button control and LED feedback are optically isolated from the speaker's internal circuitry.
- Self‑Powered – ESP32‑C6 runs from an independent 3.3 V mini PSU, neatly housed inside the speaker enclosure.
- Power On/Off – emulates long press to turn speakers on or off.
- Mode Selection – switches between
MusicandMonitoringmodes (double‑click simulation). - Mute – toggles mute function with a short press, while the LED blinks accordingly.
- True State Sync – reads the actual LED status (red/green) via isolated inputs to keep HA in sync, even when the physical button is used.
- Blink Detection – intelligently detects blinking LEDs to report mute state accurately.
- Optimistic UI – instant feedback in Home Assistant, with self‑correction if commands fail.
- Thread / Matter Ready – uses OpenThread for future Matter integration (ESP32‑C6).
The device is wired in parallel with the encoder button and the red/green LEDs of the Edifier MR4. All connections use optocouplers to ensure complete electrical isolation. The ESP32‑C6 is powered by a dedicated 3.3 V supply (e.g., small AC‑DC module) mounted inside the speaker cabinet. Commands from Home Assistant trigger simulated button presses of varying lengths:
| Action | Simulation |
|---|---|
| Power On/Off | Long press (~2 s) |
| Toggle Mute | Short press (~150 ms) |
| Change Mode | Double short press |
LED states are monitored through additional optocouplers, allowing the ESP32‑C6 to detect steady glow (mode indication) and blinking (mute active) without any electrical connection to the speaker's internal voltages.
- ESP32‑C6 development board (e.g., ESP32‑C6‑DevKitC‑1)
- 3× PC817 Optocouplers (or equivalent) – one for button simulation, two for LED sensing
- Resistors 220–470 Ω (for optocoupler LEDs)
- Independent 3.3 V power supply (small AC‑DC module or DC‑DC converter, placed inside the speaker)
| ESP32‑C6 Pin | Signal | Edifier MR4 Connection (via optocoupler) |
|---|---|---|
| GPIO19 | Red LED sense | Optocoupler input → red LED anode/cathode |
| GPIO18 | Green LED sense | Optocoupler input → green LED anode/cathode |
| GPIO20 | Button control | Optocoupler output in parallel with encoder button |
⚠️ Important: All connections to the speaker are made through optocouplers. Do not directly connect GPIO pins to the speaker circuitry. The ESP32‑C6 is powered by its own isolated 3.3 V supply – do not draw power from the speaker's internal rails.
The full YAML configuration is available in edifier-mr4.yaml. Key components:
globalsfor mode tracking and mute state.binary_sensorto read LED states (via optocouplers) with blink detection.intervalthat analyses LED toggling to detect mute blinking.switchentities for power and mute.selectentity for mode switching.
- Flash ESPHome to your ESP32‑C6 using the ESPHome Dashboard or
esphome run. - Assemble the hardware inside the speaker cabinet – connect optocouplers to the button and LED pads, and provide 3.3 V power to the ESP32‑C6.
- Add the device to Home Assistant – it will be auto‑discovered via the ESPHome integration.
- Control your MR4 monitors from HA dashboards, automations, or voice assistants!
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