What I'm trying to do:

I recently bought an iPhone 3GS (yes iPhone...) and I am going to install Android on it so I can make apps myself for it and incorporate it in a bigger project, using the WiFi and the touchscreen capabilities to interface with my Arduino.

The iPhone is soon to be jailbroken and it is not connected to a 3G network.

Technology behind it:

Like I said earlier, I am going to jailbreak it so I can install Android on it. Then, I'm going to connect this cable that will split the headphone and microphone signal to it and then connect it to my Arduino. This is where I get stuck. I want the Arduino to generate signals to the "iDroid App" and it to also send signals back.

What circuits should I implement for the microphone and speaker?

I have seen this question, but it doesn't cover microphones, and I can't find out how to actually do anything with the information. I've seen this also, and although it has awesome code samples, it doesn't explain the circuits. These aren't really duplicates, they are related, but I need further explanation and help.

  • \$\begingroup\$ even i have the same problem.but i could get some data out from the android tablet(i used DTMF method) then, i used DTMF decoder IC to decode the sound into data.its simple idea.if you need that i can give you schematic and android app source. \$\endgroup\$
    – yogece
    May 31, 2013 at 14:43
  • \$\begingroup\$ @yogece Sure: give that. That will only cover half of the question though... do you know how to send the data BACK to the iPhone then? Even if you don't, it would help me and get me going in the right direction with the back to iPhone. \$\endgroup\$ May 31, 2013 at 14:57
  • \$\begingroup\$ i invite you to chat.stackexchange.com/rooms/15/electrical-engineering lets discuss \$\endgroup\$
    – yogece
    May 31, 2013 at 15:09
  • \$\begingroup\$ @yogece just joined \$\endgroup\$ May 31, 2013 at 15:11

1 Answer 1


Have a look at this project. From what I gather, its an open source project and has some documentation on it (I didn't actually read it)

Android Oscilloscope

They used the microphone input (similiar to what you are doing) and then displaying it through an app (also open source). If you go over their stuff, you should be able to figure out, how they are reading back values. You can then write your own app so that, if you see a specific voltage, voltage range, or a specific frequency ( fft or other algorithm), you can do something with your app, or send data out through the headphones.

To send data to your iphone/android device, you would need to generate an voltage or voltage signal. That can probably be done using PWM and a low pass filter. I don't know what safe voltages are for cell phone microphone inputs, so find that out too.

Hopefully, this is a start to aid you in your research.

I haven't done any of the things I said, so do your research!


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