2 questions about packet size in USB and FPGA

GNU Radio
1

Hi

On the output path of the FPGA there’s a FIFO, Is 512 byte the size of
each packet stored in FIFO?
If true, why do I have option for fusb_block_size = 1024?
I think it would be better to send 512 byte packets instead of 1024 to
avoid fragmentation

Thank’s in advance

Juan Q.

2

On Mon, Jun 14, 2010 at 10:16 AM, Juan Q. [email protected] wrote:

Hi

On the output path of the FPGA there’s a FIFO, Is 512 byte the size of each packet stored in FIFO?
If true, why do I have option for fusb_block_size = 1024?
I think it would be better to send 512 byte packets instead of 1024 to avoid fragmentation

The simple answer is buffering. The host controller transparently
splits the transfer into appropriately sized packets, which are 512
bytes in this case. Whether it’s better to use jumbo sized transfer
blocks or more of a smaller size has more to do with the driver
implementation on the host than the USB device.

Thomas