Hi,

I have developed a device to read data from our radar DAQ chassis but I am having some latency problems. I was using bulk transfers (EP2 quad buffered 512 bytes) and I am now trying to use iso transfers instead (EP2 double buffered 1024 bytes).

I use the GPIF to read from the 96kbyte FIFO in the DAQ, and this worked fine when I was using a bulk EP, however now that I have switched to iso it doesn't do anything. My code triggers a GPIF FIFO read but nothing happens apart from the GPIF saying it's busy.

The GPIF FIFO read is just.

// GPIF Waveform 2: FIFO Rea                                                               
//                                                                                        
// Interval     0         1         2         3         4         5         6     Idle (7) 
//          _________ _________ _________ _________ _________ _________ _________ _________
//                                                                                         
// AddrMode Same Val  Same Val  Same Val  Same Val  Same Val  Same Val  Same Val           
// DataMode NO Data   Activate  Activate  Activate  Activate  Activate  Activate           
// NextData SameData  SameData  SameData  SameData  SameData  SameData  SameData           
// Int Trig No Int    No Int    No Int    No Int    No Int    No Int    No Int             
// IF/Wait  Wait 3    IF        Wait 1    Wait 1    Wait 1    Wait 1    Wait 1             
//   Term A           QTR                                                                  
//   LFunc            OR                                                                   
//   Term B           IntReady                                                             
// Branch1            ThenIdle                                                             
// Branch0            ElseIdle                                                             
// Re-Exec            No                                                                   
// Sngl/CRC Default   Default   Default   Default   Default   Default   Default            
// REQ          0         1         1         1         1         1         1         1    
// CTL1         0         0         0         0         0         0         0         0    
// CTL2         0         0         0         0         0         0         0         0    
// CTL3         0         0         0         0         0         0         0         0    
// CTL4         0         0         0         0         0         0         0         0    
// CTL5         0         0         0         0         0         0         0         0    


So there's no decision state to stall on or anything.

Anyone have any clues?

Replugging the device made it work.. So I guess I'm not resetting it properly and had caused a problem with earlier messing around.