MIDI-OX User Forum - Print Page


    
      
        MIDI-OX User Forum
        (http://www.midiox.com/cgi-bin/yabb/YaBB.pl)
      

        MIDI-OX >> MIDI-OX Bug List >> SYSEX bug revisited...
        
(Message started by: ossandust on Aug 10^th, 2008, 7:54am)

Title: SYSEX bug revisited...
Post by ossandust on Aug 10^th, 2008, 7:54am

Hi,

after days of searching and experimenting, I found an older thread on this forum describing exactly the same problem I am having.
When sending a sysex which is bigger than the buffer size, the sysex message gets corrupted.
I have developed an USB-MIDI interface, and was doing tests with this device. Since I did not have the same problem with a MidiSport 2x4 interface, I suspected an issue with my device firmware or USB stack.
Using an extremely small buffer size of 6 clearly shows the problem (while the same occurs with bigger buffer sizes)

Sent SYSEX :
F0 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 F7

Received packets in the USB controller endpoint :
04 F0 01 02
04 03 04 05
00

04 00 06 07
04 09 10 11
00

04 00 12 13
04 15 16 17
00

04 00 18 19
05 F7
00

So each first message of a packet is corrupted.
Maybe Jamie OConnell is still around and has an update on this issue? I am trying to use my device as "class compliant" on Windows-XP, I guess this is the cause? Any idea what the behavior would be on other OSes? (Vista, MacOSX)

Thanks for any additional info,
Xavier