we are currently trying to use a Cypress FX2LP for audio streaming
(isochronous adaptive endpoints) with the WinXP USB-audio-class driver.
We have already established the audio control parts (volume, mute, etc.),
and now we're trying to stream audio data to the device.
At first we're trying to make the CPU show us that data arrived, then
clear the buffers for more data.
WinXP selects the right interface, sets the sampling rate and starts to
send data, but we do not get any of it into the FX2LP. We tried
for some weeks now, all to no avail.
What we found out is that Windows sends data with Length values = 0 (this
is okay, because it's not in the USB spec for isochronous streaming),
but the Cypress streaming driver sends Length values, which maybe the
So maybe anybody experienced the same?
Reply by ●March 10, 20062006-03-10
> What we found out is that Windows sends data with Length values = 0 (this
> is okay, because it's not in the USB spec for isochronous streaming),
> but the Cypress streaming driver sends Length values, which maybe the
> must have?
Sounds like a non-standard format. The Micosoft USB audio driver only works
with standard formats, as defined in the USB audio class specification.
Anyway, try asking Cypress support.
Reply by X-Rocka●March 11, 20062006-03-11
thanks for your answer.
Yes we contacted Cypress, their first response came very fast,
then after we found out this length problem, they seemingly need some
time to investigate.
Anybody out there who can recommend a certain chip for audio
streaming? I mean high speed and lots of channels!