MP3Car.com - View Single Post - Renault "Tuner List" Head Unit/CD changer hacking

Vicne · 02-14-2006, 03:49 AM

Quote: Originally Posted by Ale

I think that something go wrong with level 0 threshold becouse the recalculated CRC of the frame 3D 01 FE FD isn't correct (3F instead of 0).

Well, indeed :
- either this frame is a special connection attempt "Anybody there ?" that doesn't follow the normal format. Not only is the CRC wrong, but also the length which should be 0
3D : start frame
01 : frame ID
FE : length (not !)
FD : CRC (not !)

- or there's a decoder error. But it would be perfectly reproductible 3 times in a row, while bytes 3D and 01 are decoded OK ? Strange...

I'd be tempted to think it's a special message that isn't in the "frame format"...

BTW, just to make sure : that's the message he saw when reading the Tx from the HU while no changer was connected, right ?

02-14-2006, 03:49 AM	#76
Vicne Variable Bitrate Join Date: Apr 2005 Location: Belgium Posts: 325	Quote: Originally Posted by Ale I think that something go wrong with level 0 threshold becouse the recalculated CRC of the frame 3D 01 FE FD isn't correct (3F instead of 0). Well, indeed : - either this frame is a special connection attempt "Anybody there ?" that doesn't follow the normal format. Not only is the CRC wrong, but also the length which should be 0 3D : start frame 01 : frame ID FE : length (not !) FD : CRC (not !) - or there's a decoder error. But it would be perfectly reproductible 3 times in a row, while bytes 3D and 01 are decoded OK ? Strange... I'd be tempted to think it's a special message that isn't in the "frame format"... BTW, just to make sure : that's the message he saw when reading the Tx from the HU while no changer was connected, right ? __________________ Vicne SPDIF CarPC V2 - Tuner List CD Changer Emulator - Chris Conty Last edited by Vicne; 02-14-2006 at 05:14 AM.