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Subject: Re: CD Changer emulation?
From: jobarjo (jobarjo78_at_yahoo.fr)
Date: 2004-03-01


Do you have a pointer to the VW project?
What is its status? started, finished?

This protocol sound ok to me.
there are some inquiry missing (track and disk names)

----- Original Message -----
From: "[IDC]Dragon" <idc-dragon_at_gmx.de>
To: "Rockbox development" <rockbox_at_cool.haxx.se>
Sent: Sunday, February 29, 2004 11:51 AM
Subject: Re: CD Changer emulation?

> For the car CD changer commands towards the Archos, I once made a
> "specification". At that time I thought I need an external controller. But
the VW folks
> do, and my spec is still the basis for that project.
>
> The remote control always sends bytes with 9600 Baud and with the upper 2
> bits set (0xC0-0xFF), the lower bits depend on the buttons. So it uses one
> "quadrant" of the available byte range. For the changer control, I thought
it
> would be a good idea to occupy another quadrant, 0x80-0xBF, for
single-byte
> commands to the Archos. I decided that commands should always be single
bytes, to
> avoid sync problems. The answer can be multibyte, though. The Archos is
the
> slave, never sends anything "unsolicited", it always has to be asked first
> (poll if necessary). I tried to logically group the commands, quick
decoding
> can be made by the first hex digit.
>
> Here's my old spec:
>
> Commands towards Archos
> -----------------------
>
> Commands:
> - 0x80 ping
> - 0x81 power off
> - 0x82 resume after powerup
> - 0x83 play
> - 0x84 pause
> - 0x85 stop
> - 0x86 start FF
> - 0x87 start FR
> - 0x88 next track
> - 0x89 previous track
> - 0x8A first track
> - 0x8B last track
> - 0x8C next random track
> - 0X8D previous random track
> - 0x8E-0x8F reserved
>
> Commands for Play-mode:
> - 0x90 normal play (special modes off)
> - 0x91 disk shuffle mode on
> - 0x92 magazin shuffle mode on
> - 0x93 intro scan on
> - 0x94 repeat one on
> - 0x95 repeat all on
> - 0x96-0x9F reserved
>
> CD select buttons:
> - 0xA0-0xA5 button n (1-6)
> - 0xA6-0xAF reserved
>
> Inquiry commandos:
> - 0xB0 give play status: state (changing, etc) (return payload: 2 byte
> flags, tbd)
> - 0xB1 give disk status: #of tracks (return payload: 16 Bit little endian)
> - 0xB2 give current track # (return payload: 16 Bit little endian)
> - 0xB3 give current track time (return payload: seconds as 16 Bit little
> endian)
> - 0xB4-0xBF reserved
>
>
> Answer to the Inquiry Commands
> ------------------------------
>
> Byte 1: negated command byte
> Byte 2: length of "payload", 0-255 Bytes
> Byte 3...n-1: Payload
> Byte n: Checksum, 8-bit sum of Bytes 1 to n-1
>
>
> Answer to all commands except inquiry commands is 1 byte error code:
> --------------------------------------------------------------------
> 0x00 Success
> 0x01 Wait (the requested action has been started, but not completed yet,
> maybe kepp polling?)
> 0x02-0xFF error codes, tbd
>
>
>
>
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