AnsweredAssumed Answered

USB max Isochronous packet size.

Question asked by Pedro Erencia on Jul 8, 2014
Latest reply on Jul 10, 2014 by Pedro Erencia

Hello,

 

we are trying to setup an MK50X256CLL100 to do Isochronous transfer with packet size of 1023. We have modified the audio example on the USB stack and, basically, changed the packet size in the descriptor from 64 to 1023. That did not work . After some tests, we discovered that up to 479 packet size the transmissions were done correctly. After that (480), even though the descriptor appears correct when doing an lsusb, the USB stack seems to not reach the callback when an URB is sent (and usbmon says it has been sent).

 

So, is there any limitation on Isochronous Endpoints ? Why thismysterious number (480) ? Are we forgetting to do something more on the descriptor configuration ?

 

Thanks

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