On Wed, Nov 07, 2007 at 03:40:44PM +0100, Uwe Bonnes wrote: > Hello, > > the last day I am banging my head against the problem how the data is > structured for the USB transfer between the FX2 and the PC. Datasheet, > FX2 reference and the web didn't givve me the right clue. > What I understand: > - the FPGA pumps interleaved samples into the FX2 fifo via GPIF. E.g. > http://www.nd.edu/~jnl/sdr/docs/tutorials/4.html talks about a sequence > I0 Q0 I1 Q1 I2 Q2 I3 Q3 I0 Q0 I1 Q1, etc. > - these samples are somehow grouped into 512 byte blocks and sent over USB > - the PC receives these blocks and must somehow know where a data group > starts > > I can only think that always 512 byte blocks are transferred. With a > full number of data groups fitting into the block, the block would always > start with I0. But what happens if the PC gets out of sync, by not reading a > full block with some strange event? Then the next 512 byte blocks read would > always start somewhere in the datagroup. Any way to resync? Are short > packets and the PKTEND signal used? > > Thanks for any hints > > -- > Uwe Bonnes [EMAIL PROTECTED]
We never transfer a short block. They are always 512 bytes long. There's no problem keeping track of the proper alignment. Eric _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
