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Subject: Re: Telechips-based players

Re: Telechips-based players

From: Punit Agrawal <punit_at_cs.mcgill.ca>
Date: Tue, 31 Jul 2007 12:49:52 -0400

On July 31, 2007 05:21:08 Dave Chapman wrote:
> Basil Dozhdalev wrote:
> > Hello,
> >
> > Had anyone ever try to develop Rockbox for Telechips-based
> > MP3-players?
>
> I wouldn't say I'm trying to develop Rockbox for the Telechips
> players, but I do have such a device (a small flash-based MP3/WMA
> player with DAB radio). This has a TCC773L.
>
I have the Cowon D2 (TCC7801) which I was trying to understand to check
the feasibility of a port. There are still a lot of unknowns but some
of what you say about the firmware matches up with my notes too. Except
that I didn't know about the jump. So one more piece of the puzzle in
place.

> I've been collecting the firmware files for various telechips-based
> players, and it seems the firmware is unencrypted, but there are two
> 32-bit numbers in the headers (most likely a checksum and/or
> signature) which I haven't been able to figure out.
>
> So if your SDK can provide any clues to those, it would be helpful.
> Hopefully the 77x and 76x share a lot in common.
>
> As an example, the header for the firmware update for my Logik
> MP3/DAB player looks like this:
>
> 0000000: a0f3 9fe5 0601 ffff 5665 723a 3030 3731 ........Ver:0071
> 0000010: 05e8 fdea 0000 0000 be26 f687 18cd 0c00 .........&......
>
> My understanding so far is as follows:
>
> 0x00 - An ARM branch instruction (ldr pc, [pc, #xxx]) to the entry
> point on the firmware.
> 0x04 - 0601 in all firmwares I've looked at - version?
> 0x06 - 0xffff in all firmwares I've looked at
> 0x08 - "Ver:0071" string (in all firmwares)
> 0x10 - Unknown 32-bit number
> 0x14 - Zero in all firmwares I've looked at
> 0x18 - Unknown 32-bit number
> 0x1c - Length of firmware file in bytes
>
> Understanding those two unknown numbers and hence being able to
> generate firmware files accepted by the firmware upgrade feature of
> the original firmware would be a good start to any port.
>

Yeah it would be a bit help if from the SDK, you can find the
tools/method used to create the firmware and pack the files etc. Having
one SDK might just make it possible for a lot of dependent devices to
be understood/ported.

There are a few people on Cowon forums interested in a rockbox port for
the D2. If things start moving I have a feeling more people will join
in the efforts.

Cheers!

Punit
> Regards,
>
> Dave.
Received on 2007-07-31


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