Read data through iPhone audio jack

Question

I am looking for a way to read raw data that is being sent from the Arduino through iPhone's audio jack.

I searched a lot and found this which detects whether a jack plug is connected or not but couldn't find any code to read the raw data.

Any help in this regard will be greatly appreciated!

Thanks.

Answer 1

If the bandwidth of the incoming signal fits into the bandwidth of the iPhone's A/D converter (± 20Hz to 20kHz) you can read it.

You'll need audio jack to audio jack cable with Tip/Ring1/Ring2/Sleeve pinout (Balanced plug on the picture) on both sides (Tip/Ring/Sleeve (Conventional stereo plug) won't work).

The incoming signal will be analogue so you'll need to convert it (through Frequency-shift keying modem) to digital, this modem library should do the trick (I've used it to convert into digital, unfortunately I do not have my old project to share but it's tested):

https://github.com/jensmeder/FSKModem https://en.wikipedia.org/wiki/Frequency-shift_keying

Also take a look at this lib (Did you try it? Maybe it will help better in your case):

https://github.com/billhsu/jackDuino

Also check this out (Audio Jack Modem for iPhone):

https://www.sparkfun.com/products/retired/10331