Hi Darek,
I thought I solved this issue but it came up again.
From time to time I get the late command error. I get it when calling
the revc method for the receive stream. In that moment there is no data
returned from the call (return value is 0). I get these results a couple
of times and after that the error code indicates timeout error and I get
no more data - never. My program is stuck while waiting for the
requested data to arrive.
If I understood corretly this should not be the case. I should get the
data anyway, right?
Best regards,
Fabian
Am 07.06.2018 um 13:47 schrieb Derek Kozel:
Hello Fabian,
Commands which are late will be executed anyways and return the error
notification which you are seeing. Commands after it are also executed.
Depending on your application it is often possible to structure the
commands such that get_time_now only needs to be called in the beginning
and the act of receiving can be used to keep track of the device time.
The TwinRX fast frequency hopping example does this, allowing for
continuous and stable frequency hopping and burst receiving at a very
high rate.
Regards,
Derek
On Thu, Jun 7, 2018 at 12:12 PM, Fabian Schwartau via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>> wrote:
Hi everyone,
I am currently working with timed commands to perform synchronized
reception of multiple channels. As the timing is quite critilical I
would like to use quite low delay I add to usrp->get_time_now() for
the next command(s). However, sometimes it happens (even with quite
high values like 20ms) that I get an late command error when reading
the data from the stream. I guess this can happen from time to time
if the thread was interrupted by the OS to do other stuff. And this
is not a problem, if it happens just from time to time. But I don't
know how to handle the problem.
Is the command that was too late executed anyway? What about the
commands after that?
Is there is simple way to get in a clean state after receiving this
error? Like delete all commands in the queue and clear all buffers?
I am using two USRP X310 with each 2 TwinRX. PPS, 10 MHz and LOs are
synchronized over all boards.
Best regards,
Fabian
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