Re: N210 DAC and ADC usage

[Marcus Müller]

Just realized that there *is* a C++ API:

usrp_block->get_device()->get_rx_dboard_iface()->read_aux_adc();

replace _rx_ with _tx_ for the LFTX, and read_aux_adc with write_aux_dac for 
the DAC.

Best regards,
Marcus

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On 05.03.22 13:31, Marcus Müller wrote:
> Hi Fabien,
>
> no need to modify the FPGA. The functionality is there – it's just not exposed to the 
> user. Also, note that interacting with the auxiliary ADC and DAC is going to be 
> asynchronous to the sample flow – there might be millions of samples from the main ADC 
> that have flown by before an AUX_DAC setting takes effect!
>
> You also don't really need to modify UHD – you *can* use the UHD property tree (through 
> uspr_block->get_device()->get_tree()->access() ), it's just not a proper, stable, 
> well-tested, failure-checking API.
>
> Best regards,
> Marcus
>
> On 04.03.22 15:01, Fabien PELLET wrote:
> > Yes, sorry indeed I was talking about AUX_DAC and AUX_ADC that are replicated from the 
> > motherboard.
> >
> > I already use IO which works very well. So there is no way to send samples (or receive) 
> > at a specific sample rate using that AUX_DAC or ADC. It is just some "analog IOs" for 
> > reading some external sensors for example if I understand well what you wrote.
> >
> > What are the specifications of that AUX ?
> >
> > Using a specifique FPGA firmware and custom UHD library, would it be possible to 
> > transform them as GR source or sink ?
> >
> > Thanks,
> >
> > Best regards,
> >
> > Fabien, F4CTZ.
> >
> > Le 04/03/2022 à 14:35, Marcus Müller a écrit :
> > > Sorry, hit "send" accidentally:
> > >
> > > Dear Fabien,
> > >
> > > there's no ADC on these daughterboards. Just an EEPROM for identification, opamps for 
> > > amplification and signal conditioning, and on the LFTX a switch-mode power supply. 
> > > You're right, they do exppose the AUX DACs and ADC lines from the motherboad.
> > >
> > > However, these are without further ado not accessible from UHD, and thus also not from 
> > > GNU Radio. Some daughterboard drivers use them.
> > >
> > > I'm not sure UHD exposes them in all version, but `uhd_usrp_probe --tree` might show 
> > > properties called "AUX_DAC_A" (or _B, or AUX_ADC_.., you get the idea). You can use 
> > > get_device() on your USRP blocks and access theses properties from your GNU Radio 
> > > program (from C++), but it's not really an API – more an exposing of intestines...
> > >
> > > Best regards,
> > > Marcus
> > >
> > > On 04.03.22 14:30, Marcus Müller wrote:
> > > > Dear Fabien,
> > > >
> > > > there's no ADC on these daughterboards. Just an EEPROM for identification, opamps for 
> > > > amplification and signal conditioning, and on the LFTX a switch-mode power supply.
> > > >
> > > > Best regards,
> > > > Marcus
> > > >
> > > > On 04.03.22 10:30, Fabien PELLET wrote:
> > > > > Hello,
> > > > >
> > > > > As there are IOs available on LFTX and LFRX, there are also ADC and DAC 
> > > > > available.
> > > > >
> > > > > Is there a way to use them as SOURCE and SINK in gnuradio for low speed 
> > > > > conversion ?
> > > > >
> > > > > Thanks,
> > > > >
> > > > > Best regards,
> > > > >
> > > > > Fabien, F4CTZ.