title: iPhone headphone jack - read in data?
body: <p>I have a small device which connects to a battery powered monitor. When I turn the wheel on the device, the monitor displays information such as when you started turning the wheel and how fast the wheel is turning. I believe the device is sending some sort of magnetic pulse or something through the <a href="http://en.wikipedia.org/wiki/TRS_connector" rel="noreferrer">3.5&nbsp;mm audio jack</a>.</p>
  
  <p>Instead of connecting the device to its original monitor, I want to connect it to my <a href="http://en.wikipedia.org/wiki/IPhone" rel="noreferrer">iPhone</a> and read in the same data. The cord has a 3.5&nbsp;mm audio jack at the end and fits in the iPhone normally like a headphone.</p>
  
  <p>I have looked into projects like <a href="http://www.eecs.umich.edu/~prabal/projects/hijack/" rel="noreferrer">HiJack</a> but am unsure of how to use the data I receive (or where the data is actually coming from when I do receive it), or if I can even use it in this circumstance.</p>
  
  <p><strong>Can I read data in (to the iPhone) from an external device through the iPhone's audio jack?</strong></p>
  
  <p><strong>If yes, what frameworks/libraries do you suggest I look into?</strong></p>
  
  <p>I have looked into <a href="http://developer.apple.com/library/ios/#samplecode/aurioTouch/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007770" rel="noreferrer">AurioTouch</a> by Apple, but it seems rather complicated and isn't very straightforward.  </p>