I'm looking for a way to detect microphone/headset/headphones. How I can detect if two pins of audio jack has been shorted? This is te easiest way to check what kind of equipment has been plugged in. In this situation i would check short circuit bewteen pin 2 and 3. I'm using ADAU1761 and 4 pin jack.

  1   2   3   4
|-----------\\\\
|GND|GND|GND|MIC
|-----------////

|-----------\\\\
|MIC|GND|RHP|LHP
|-----------////

|-----------\\\\
|GND|GND|RHP|LHP
|-----------////

Any idea?