Re: [Discuss-gnuradio] gr-uhd timed command messages

[Marcus D. Leech]

On 03/04/2016 07:59 AM, Nigel Steed wrote:
> Hi Marcus/Martin,
>
> I have got it stable now. Though I don't think the timed commands are doing 
> what I think.
>
> I have re-built gr-uhd just to print out the fract and full secs from the time 
> command which as you say is 2 seconds - which is ok for testing now.
>
> If I send a time command, does the gr-uhd get the current time and add the 2 
> seconds. As I am sending a command message to the UHD Source for both mother 
> boards (I have two N210 on one UHD Source) in separate messages and not sure 
> how that will work.
>
> Also, I do not see a delay of data for 2 seconds from the UHD Source, when 
> perfomed in python it seems to block until the time has been reached.
>
> Does my code below look reasonable ?
>
> Thanks,
>
> Nigel
I'll point out that command times, like other times in the UHD universe 
are absolute times, as seen by the USRP device:

http://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a191b78b00d051d3d51c2f719361c1fb5

Also, there should be no reason to set the times separately for each 
mboard, the API allows you to specify ALL_MBOARDS.


>         // Send a receiver timed command - motherboard 0
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("mboard"), 
> pmt::mp(0));
>               pmt::pmt_t timeStamp = pmt::cons(pmt::from_long(1), 
> pmt::from_double(1));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"), 
> timeStamp);
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>               // Send a receiver timed command - motherboard 1
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("mboard"), 
> pmt::mp(1));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"), 
> timeStamp);
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>               // Tune receiver channel 0
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("freq"), 
> pmt::mp(d_txFrequency));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("chan"), 
> pmt::mp(0));
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>               // Tune receiver channel 1
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("freq"), 
> pmt::mp(d_txFrequency));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("chan"), 
> pmt::mp(1));
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>               // Tune transmitter
>               d_txCommand = pmt::make_dict();
>               d_txCommand = pmt::dict_add(d_txCommand, pmt::mp("freq"), 
> pmt::mp(d_txFrequency));
>               d_txCommand = pmt::dict_add(d_txCommand, pmt::mp("chan"), 
> pmt::mp(0));
>               message_port_pub(pmt::mp("tx_freq_msg"), d_txCommand );
>
>               // Clear the receiver command time - motherboard 0
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("mboard"), 
> pmt::mp(0));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"), 
> pmt::PMT_NIL);
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>               // Clear the receiver command time - motherboard 0
>               d_rxCommand = pmt::make_dict();
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("mboard"), 
> pmt::mp(1));
>               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"), 
> pmt::PMT_NIL);
>               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
>
>
>
>
>
> -----Original Message-----
> From: Marcus Müller [mailto:address@hidden
> Sent: 04 March 2016 10:44
> To: Nigel Steed <address@hidden>; address@hidden
> Subject: Re: [Discuss-gnuradio] gr-uhd timed command messages
>
> Hi Nigel,
>
> from_long(1), from_double(1)
> implies that your timestamp is at 1 [full second] + 1 [fraction of second] = 
> 2s; usually you'd do from_long(2), from_double(0) for that :)
>
> > Do you think it maybe better for me to modify UHD Source and implement the 
> > timed command in the set_center_freq function in the usrp_source_impl.cc (UHD 
> > Source Block) ? As I am successfully stepping the UHD Source using the message 
> > port successfully and I just need to add a timed command so both channels 
> > re-tune together.
> Not quite sure. As far as I can tell, the usrp_source does exactly the timed 
> command tuning when you issue these commands; however, I've to admit I haven't 
> read up on your discussion with Martin, so there might be a bug and it doesn't?
>
> Best regards,
> Marcus
>
>
> On 04.03.2016 11:35, Nigel Steed wrote:
> > Thanks Marcus,
> >
> > The UHD Source finally understand the following:
> >
> > pmt::pmt_t timeStamp = pmt::cons(pmt::from_long(1),
> > pmt::from_double(1)); d_rxCommand = pmt::dict_add(d_rxCommand,
> > pmt::mp("time"), timeStamp);
> >
> > Although UHD Source reports processing the message, I eventually get a packet 
> > loss error and the N210 disconnects (no control response error).
> >
> > Do you think it maybe better for me to modify UHD Source and implement the 
> > timed command in the set_center_freq function in the usrp_source_impl.cc (UHD 
> > Source Block) ? As I am successfully stepping the UHD Source using the message 
> > port successfully and I just need to add a timed command so both channels 
> > re-tune together.
> >
> > Thanks,
> >
> > Nigel
> > -----Original Message-----
> > From: address@hidden
> > [mailto:address@hidden On
> > Behalf Of Marcus Müller
> > Sent: 04 March 2016 08:35
> > To: address@hidden
> > Subject: Re: [Discuss-gnuradio] gr-uhd timed command messages
> >
> > Hi Nigel,
> >
> > >              d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"),
> > > pmt::mp(0.5));
> > Timestamps aren't just doubles for UHD; they ought to be [1]
> >
> > > timestamp: A pair composed of (long full_secs, double frac_secs).
> > Similar to uhd::time_spec_t.
> >
> > So your timestamp needs to be a pair of long, double
> >
> > pmt_t timestamp = pmt::make_pair(pmt::from_long(0),
> > pmt::from_double(0.5)); d_rxCommand = pmt::dict_add(d_rxCommand,
> > pmt::mp("time"), timestamp);
> >
> > if I'm not mistaken.
> >
> > Best regards,
> > Marcus
> >
> > [1]
> > https://gnuradio.org/doc/doxygen/page_uhd.html#uhd_command_syntax_cmds
> > On 04.03.2016 01:39, Nigel Steed wrote:
> > > Hi Martin,
> > >
> > > I have put the following code into my block.
> > >
> > >
> > >         d_rxCommand = pmt::make_dict();
> > >               d_rxCommand = pmt::dict_add(d_rxCommand, pmt::mp("time"), 
> > > pmt::mp(0.5));
> > >               message_port_pub(pmt::mp("rx_freq_msg"), d_rxCommand );
> > >
> > > It sends the message to the UHD Sink. But I get this error at run time:
> > >
> > >         thread[thread-per-block[5]: <block gr uhd usrp source (1)>]: pmt_cdr:
> > > wrong_type : 1
> > >
> > > Any ideas ? I am trying to auto step the frequencies, and currently have my own 
> > > block to generate frequency messages which works fine. I am now trying to 
> > > implement the time commands. Is there any other way to do it ?
> > >
> > > Thanks,
> > >
> > > Nigel
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: address@hidden
> > > [mailto:address@hidden On
> > > Behalf Of Martin Braun
> > > Sent: Wednesday, March 2, 2016 9:24 PM
> > > To: address@hidden
> > > Subject: Re: [Discuss-gnuradio] gr-uhd timed command messages
> > >
> > > When using messages, simply add a 'time' key to the command dictionary, and it 
> > > will be set for the command you're calling. The time stamp value, is a 
> > > long/double pair, for full and fractional time. Example:
> > >
> > > {'freq': 1e9, 'time': (100, 0.1)}
> > >
> > > If this is your message, it will set the frequency to 1 GHz at time 100.1.
> > >
> > > Cheers,
> > > Martin
> > >
> > >
> > >
> > > On 03/02/2016 05:46 AM, Nigel Steed wrote:
> > > > Hi,
> > > >
> > > >   
> > > >
> > > > Anyone know or managed to implement the time command using a message
> > > > port to the UHD Source Block ?
> > > >
> > > >   
> > > >
> > > > I believe time commands are not implemented in the latest GNURadio
> > > > gr-uhd ? Is that correct ?
> > > >
> > > >   
> > > >
> > > > Thanks,
> > > >
> > > >   
> > > >
> > > > Nigel
> > > >
> > > >
> > > >
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