How to use the button on a headset?

Question

I want to implement push to talk on my custom PCB.

I apply a 2V DC bias on the microphone line of the jack through a 2.2k resistor. While pressing the button of the headset I see the resistance between MIC and GND fall to 1.3ohms (I guess the exact value will change with different headset.)

My question is:

Can I still use the microphone while the button is pressed? If I can can you tell me if I can directly send the MIC to my MCU (for detection of the button) and to my microphone amplifier.

I've read the Android documentation but I didn't answer my question.

Yes It's a standard headset by Sony compatible with Android, It only got a button (function A on the drawing in the first answer) — VicMac, Feb 07 '22 at 14:23

score 1 · Accepted Answer · answered Feb 07 '22 at 13:01

1

Figure 1. Source: Android.com

Can I still use the microphone while the button is pressed? If I can can you tell me if I can directly send the MIC to my MCU (for detection of the button) and to my microphone amplifier.

According to Figure 1 pressing Button A will short-circuit the microphone. You will get no audio from the mic while the button is pressed. The MCU can detect the button press by the monitoring V_eq which will fall to zero.

answered Feb 07 '22 at 13:01

Transistor

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I've read the doc it seems that I can't do push-to-talk this way, I want to know if another way exist – VicMac Feb 07 '22 at 14:24
If the button in the headset shorts out the mic signal then you can't. – Transistor Feb 07 '22 at 14:32

How to use the button on a headset?

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