Re: [Discuss-gnuradio] Auxiliary ADC

[Christoph Thein]

> Eric Blossom wrote:
> > On Wed, Jan 20, 2010 at 07:20:43PM +0100, Christoph Thein wrote:
> >>> On 01/19/2010 10:35 AM, Christoph Thein wrote:
> >>>>> On 01/19/2010 09:47 AM, Christoph Thein wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> is there a possibility to read the data coming from the auxiliary
> >>>>>> ADC (AD7922) at the moment?  I couldn't find any hint in the code or
> >>>>>> on the mailing list that could point me to a good direction to
> >>>>>> start.
> >>>>>>
> >>>>>> Just out of interest: What should the auxiliary DAC (AD5623) be used
> >>>>>> for?
> >>
> >> The USRP1 uses the read_aux_adc function to get the values. Does the
> >> read_gpio replace it for the USRP2? If not how is the USRP2 accessing
> >> the aux ADC?
> >>
> >> Cheers,
> >> Christoph
> >
> > At this point, firmware in the USRP2 controls the daughterboards, and
> > the read_aux_adc functionality is not exported to the host.
> >
> > Eric
> >
> >
> > _______________________________________________
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> > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
> Does the firmware currently do anything with the Aux ADC? I see the
> definitions for reading from the SPI controller, and the function
> (firmware/lib/lsadc.c: lsadc_read_rx(int)) which appears to be the only
> place that reads from the correct SPI device. Also, it looks like it
> would be difficult to read the value directly from inside the FPGA: i.e.
> if I wanted to use the RSSI value for an AGC or squelch control, I'd
> probably be best served by periodically reading the value from within
> the firmware, and pushing it back into a register in, e.g., dsp_rx_regs.
> This would likely mean I'd have some additional inherent delay in using
> the value in the DSP chain. Is there a better way - e.g. I assume it
> would be possible to load the data from the SPI controller in the FPGA,
> but does that come with a (much?) larger cost in terms of logic, and
> therefore area/etc.?
>  Thanks,
>   Doug
> 

Hi,

I am interested in logging the RSSI on the host's side. Therefore I am looking 
for a way to push the values from the firmware to the host. Does anybody have 
some insides how to access these registers  (written with dsp_rx_regs from 
within the firmware like mentioned by Doug) from the host. I already looked at 
the read_gpio functions but got stucked, not knowing exactly if they can 
provide the wanted functionality.  

BR Christoph