Technical Details
The Apple Remote uses an NEC IR protocol which consists of a differential PPM encoding on a 1:3 duty cycle 38kHz 950 nm infrared carrier. There are 32 bits of encoded data between the AGC leader and the stop bit:
| Protocol | on (µs) | off (µs) | total (µs) |
|---|---|---|---|
| leader | 9000 | 4500 | 13500 |
| 0 bit | 560 | 560 | 1120 |
| 1 bit | 560 | 1690 | 2250 |
| stop | 560 | 560 |
The first two bytes sent are the Apple custom code ID (0xEE followed by 0x87), which are followed by one byte command and one byte remote ID (0-255) making a total of 32 bits of data. All bytes are sent least significant bit first. The least significant bit of the command byte is a parity bit over the command byte and the ID byte. The commands consist of:
| Value | Button | Command |
|---|---|---|
| 0x02/0x03 | Menu | Menu |
| 0x04/0x05 | Center | Play/Pause |
| 0x07/0x06 | Right | Next/Fast-Forward |
| 0x08/0x09 | Left | Previous/Rewind |
| 0x0b/0x0a | Up | Volume Up |
| 0x0d/0x0c | Down | Volume Down |
The aluminium Apple remote control has 7 buttons, one more than the previous white plastic model; the extra button is a play/pause button that sends the same code as the center button. However, in order to distinguish these, both buttons prepend their code with another 32 bit sequence containing the commands 0x5f/0x5e and 0x5d/0x5c, respectively.
The remote ID consists of one byte and is used to distinguish codes sent by multiple remotes. The remote ID is changeable by holding the Next/Fast-Forward and Menu buttons for 5 seconds. The sequence of remote IDs is non-sequential but predictable following the hexadecimal digit ordering 0, 8, 4, C, 2, A, 6, E, 1, 9, 5, D, 3, B, 7, F. The byte has least significant bit first so remote ID 04 would be followed by 84 and FA would be followed by 06. Note: this ordering only verified on older, white remote model.
Read more about this topic: Apple Remote
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