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Research
A large amount of work went into determining whether this idea was actually feasible. No one appears to have made any similar efforts in 476 final projects before, and though there is a similar idea in ECE 313, that course was designed around a standard CD player and controlled the player by shorting the buttons.
We initially found the iPod Dock Connector pin-out, which is available from pinouts.ru After that, we eventually found the Apple Accessory Protocol, which is detailed best on the iPod Linux wiki.
Important Pins on the iPod
| Pin | Use |
| 1 | Ground |
| 11 | Serial Ground |
| 12 | iPod RX; microcontroller transmits on this pin |
| 13 | iPod TX; microcontroller receives from this pin |
| 21 | iPod Accessory resistor: We use 500k |
It's important to note which pins are the receive and transmit pins. On the pinouts.ru page, pin 13 is “Serial RxD,” which means serial receive from the iPod's point of view. Mixing it up could confuse you unnecessarily for a few hours.