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Vicne · 02-12-2006, 07:08 PM

Quote: Originally Posted by Putput

When the frame starts with 3D it calculates the FCS perfectly, only when it starts with 3F it goes wrong. When I change the 3F to 3D the result is ok again, so maybe the 3F could be a glitch?

I have no explanation for these 3F. It could well be a glitch indeed, because a far as I can tell, there are no more (or at least much less) frames beginning with 3F in the last dumps... But why 3F ?? OK, it's only one bit away from 3D, but there are 8 such values...
It could well be a hardware threshold problem, or just a bug in MTTTY...
Anyway, for frames we'll generate, I don't see the point in introducing errors :-), and for frames we receive, we can always throw them away thanks to the check byte (that's why checks are there in the first place :-) ).
However, it could be interesting to see if the protocol includes things such as "try again" when a received frame has to be rejected.

By the way, FCS stand for Frame Check Sequence, right ?

02-12-2006, 07:08 PM	#53
Vicne Variable Bitrate Join Date: Apr 2005 Location: Belgium Posts: 325	Quote: Originally Posted by Putput When the frame starts with 3D it calculates the FCS perfectly, only when it starts with 3F it goes wrong. When I change the 3F to 3D the result is ok again, so maybe the 3F could be a glitch? I have no explanation for these 3F. It could well be a glitch indeed, because a far as I can tell, there are no more (or at least much less) frames beginning with 3F in the last dumps... But why 3F ?? OK, it's only one bit away from 3D, but there are 8 such values... It could well be a hardware threshold problem, or just a bug in MTTTY... Anyway, for frames we'll generate, I don't see the point in introducing errors :-), and for frames we receive, we can always throw them away thanks to the check byte (that's why checks are there in the first place :-) ). However, it could be interesting to see if the protocol includes things such as "try again" when a received frame has to be rejected. By the way, FCS stand for Frame Check Sequence, right ? __________________ Vicne SPDIF CarPC V2 - Tuner List CD Changer Emulator - Chris Conty Last edited by Vicne; 02-12-2006 at 07:11 PM.