create hardware for iphone to connect with external device. arduino?

Question

hi i need to create a simple connector. I think i may need to create an arduino board that will take data from the application and then transmit them to an external device.

Answer 1

You can communicate with MFi-sanctioned devices using the External Accessory framework included in iOS. It is laughably simple (standard stream processing) to interface with these devices.

The trouble is building an MFi-sanctioned device. For both regulatory reasons (inescapable) and Apple's own policies (QA, don't want to associate with shonky hardware) the MFi Program isn't nearly as easy to get into as the iOS Developer Program. What's more, people/businesses operating in the program are under NDAs.

Building iPhone OS Accessories by Ken Maskrey is a good read and probably the most detailed account of the MFi program you'll get outside of the NDA. It answers most of the questions you've posed.

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That said, there's an alternative. If you don't mind jailbreaking your iOS device, a few of the pins in the 30-pin connector (available from Sparkfun, including a break-out board) are standard RS-232. The other pins are documented too, if that's of interest.

The serial port is available at /dev/tty.iap, a character device. There are also a few tutorials available. That all said and done, it's considerably simpler (and App Store-safe) to use 802.11 -- hopefully your device doesn't mind the extra power draw!