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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39  \subsection{Alpine CD changer emulator} This plugin emulates an Alpine CD changer. It allows to plug the Archos to a compatible head unit and control the playback from there, too. Currently implemented is track change, shuffle, seek, but no disk change. The plugin is a TSR, meaning it silently operates in the background once started. It will keep doing so until a new plugin is started. Alpine also did M-Bus as OEM for other brands (Honda, Acura, Volvo, BMW, etc.) Nowadays Alpine uses a different protocol, called Ai-Net, not supported by this plugin. (As well as all other protocols, please do not ask for such!) \subsubsection{The cable} Hookup to Archos works by connecting the headphone output including the remote pin (you need a 4-ring 3.5 mm plug for that) to the changer jack of the radio. M-Bus radios have a DIN-style circular jack with 8 pins (7 in a $\sim$ 270 degree circle, one in the center). A standard 5-pin DIN plug is OK for this, since we don't use the other (power) pins. As OEM, they shuffled the pins around a bit, better check first if it's not genuine Alpine. The bus pin is pulled high to 12 volts with a $\sim$ 2kOhm resistor, pulses driven low. Because it's open collector, this is not harmful to the Archos.\\ ASCII art of the 4-pin headphone plug: \begin{verbatim} / \ \_/ left -> Alpine pin 5 |_| right -> Alpine pin 4 |_| remote -> Alpine pin 1 |_| ground -> Alpine pin 2 + 3 \end{verbatim} The remote pin can be programmed bidirectional, that's the reason this works. Very luckily the M-Bus uses a single wire communication and the two radios I tried are happy with the 3.3 Volt level the Arcos can deliver. So the connection is a simple cable! For all protocols requiring more lines, an external controller would be necessary. \textbf{Note:} Archos FMs don't have the remote pin internally connected, but one unit that was opened was internally prepared for it, a matter of closing a bridge.