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Re: [Discuss-gnuradio] Possible bug in the vrt branch firmware?

From: Josh Blum
Subject: Re: [Discuss-gnuradio] Possible bug in the vrt branch firmware?
Date: Mon, 08 Mar 2010 11:03:43 -0800
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20100217 Shredder/3.0.3pre

There have been no recent changes to the images posted at http://www.ettus.com/usrp2_vrt

I believe that there is a problem when you tell usrp2 to start streaming at a time in the past. I cannot verify this at the moment.

Try putting a sleep(1) after the set time at next pps. By nature, set time at nest pps could take a second (worst case scenario) to latch in new values.


On 03/08/2010 10:12 AM, ValentinG wrote:

Hi All,

We've tried editing the rx_timed_samples.cc to set the time on the USRPs on
the next pps and then start streaming data some time after, by inserting the
following code (instead of the existing one) between rx_handler
my_handler(nsamples) and the while loop:

   //create a new usrp2 object, set some properties
   usrp2::usrp2::sptr u2 = usrp2::usrp2::make(interface, mac_addr_str);

   //set the system time to the usrp2
   u2->set_time_at_next_pps(usrp2::time_spec_t(0, 0));

   //begin streaming in the future
   u2->start_rx_streaming(0, usrp2::time_spec_t(2, 10000));

this code used to work in the middle of last week. We had to reflash our SD
cards on Friday, so we downloaded the firmware from
http://www.ettus.com/usrp2_vrt and flashed our cards with it. After doing
that the above code just stopped working. Was there an update of firmware
some time last week?

Strangely enough it works if we set the time of the usrps to 200,0 instead
of 0,0 and start streaming at 202, 10000. But this fix only works for one
acquisition, i.e. if we run the code one more time it just freezes and
doesn't do anything, so to run it again we have to reset the usrps.

We're using 1Hz TTL PPS as required by the USRP2 spec.

Any ideas?


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