On Fri, May 8, 2009 at 9:28 PM, Eric Blossom <[email protected]> wrote: > On Fri, May 08, 2009 at 03:43:34PM -0400, Andrew Lutomirski wrote: >> Hi all- >> >> I'm trying to re-tune a daughterboard, while acquiring samples, and I >> seem to get an overrun every time. (This is in C++.) > >> Before I start investigating really hackish ways to make this work, >> has anyone had any success getting this to work? > > I'm assuming this is on a USRP2.
Whoops, should've mentioned. This is a USRP1. > > The current firmware stops the streaming, does the tune, and restarts > streaming. This produces a discontinuity of varying length, but > doesn't underrun. > > Latest versions of the FPGA and firmware: > > http://gnuradio.org/releases/usrp2-bin/trunk/txrx_edk10.1_r10925.bin > http://gnuradio.org/releases/usrp2-bin/trunk/u2_rev3_ise10.1sp3_r10766.bin > > >> I don't actually care about the data I get while tuning, but I don't >> want to lose track of the exact time, so I'd be happy with a way to >> ask the USRP to pause for a specified number of samples, as well, or >> even just to know how many samples I lost due to the overrun. My current thought is to add a new FPGA register FR_SKIP_SAMPLES. Writing a number N to that register would cause the next N samples that would otherwise be written to USB to be skipped. The sequence would be: 1. Write 1000000 to FR_SKIP_SAMPLES. (I suspect that just a few ms worth of samples would be plenty.) 2. Tune the USRP. 3. Hope that tuning finishes before the full batch of samples have been skipped. Alternatively, I could try to modify the firmware to do i2c asynchronously, but that sounds a lot more painful. --Andy _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
