Why might the wire not work?

Question

Audio

Hello.
I am working on this idea. Data transfer must be done through an audio cable, one end of which is connected to the computer and the other to the android phone.
The problem is that adnroid does not want to accept the cable as an input source. TRRS plug.

Looking for another cable or ...?

Answer 1

The pinout doesn't match. On the phone side, everything is clear - two headphones and a microphone.
On the computer side:
1. or you plug it into the headphone/line-out jack, that is, you have a TRS connector and the signal goes to the output, not to the input.
2. or you have a headset connector (laptop / tablet), TRRS, the same situation - you get a microphone-microphone connection, and headphones-headphones.
Buy 2 jacks and wire, solder yourself. Exit to entrance. I advise you to assemble a simple resistive divider, the level at the output of the sound card is about a volt, at the microphone input 100 times less, you can overload or even burn.

Answer 2

The problem is that adnroid does not want to accept the cable as an input source.

There can be a problem not only in the wiring and levels - in the headsets there is an electret microphone, which requires coordination with the input of the microphone amplifier in the phone. The low-resistance audio output can simply connect the microphone input - you need to either experiment with decoupling (try a 0.1 uF separating capacitor), or deal purely specifically with specific hardware, chipset, headset - invite an electronics engineer and stock up on datasheets.