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| Detecting if Audio in or out is connected |
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| Hast:
Hello I am doing a product where we want to minimize the number of connectors on it. One thing we are looking at is if it is possible to combine the audio in/out connectors into one connector. The connector is an ordinary 3.5 mm audio jack connector with left/right/GND. It should be automatic detection of audio in/out. The thing is that we would need to somehow measure if it is an audio in or out that is connected and then use an analog mux to route the signal to the right place (or is there a better way?). I see some different scenarios. -Unconnected -Connected no audio -Connected audio -Connected audio out Can this be done? Can we do some kind of impedance measurement to see if it is an audio in or out? BR |
| bob91343:
Why not use a 4 pin connector. The first two are audio, the third is ground, and the fourth is grounded if it's an input and open if output. The mating connector tells the receptacle which it is. |
| Hast:
Yes, I have thought about that but the thing is that the customer should be able to use an ordinary 3 pin 3.5 mm cable. The product must be easy to use, nothing special. |
| TheUnnamedNewbie:
I'm not sure, but I seem to recall that line-audio should terminate in 600 ohm. I would imagine an audio-output source would be show a high-impedance, and an audio-input would show 600 ohm. But then again, I also know that a lot of stuff like phones and the like turn off their output amplifiers and might even short/terminate their outputs for protection? |
| NiHaoMike:
The simple way is to have the input circuit connected all the time and the output circuit connected via 1k or so resistors. Then just mute the output circuit to use the input function. |
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