I want to use the headphone output of an iPhone as a trigger to be recognised by the Pi, (which will then carry out a defined action), i.e., similar to a button push, but using the sound output of the phone, instead of a physical button.
I have a few questions.
Is the sound from an iPhone likely to be loud enough to be recognised by the Pi? If so, which pins should I be using?
If not, would one of the Audio cards, eg Wolfson, do the trick? I can see that they are capable of recording sound, but I don't want that, I want to use the sound input as a trigger.