Re: [Discuss-gnuradio] AUX_ADC Inputs and mux register docs

[Eric Blossom]

On Thu, Jul 07, 2005 at 07:14:31AM -0700, Heiko Jones wrote:
> How do I set the mux register to look at the AUX_ADC inputs? I am
> assuming it is the mux register I set, but, I searched and could find no
> documentation on what the bits of the mux register do.

You don't use the mux register to read the AUX_ADCs.  See
usrp/host/lib/usrp_{basic,standard}.h for docs on all of this stuff.
See especially usrp_basic_rx::read_aux_adc and
usrp_basic_tx::read_aux_adc

  /*!
   * \brief Read auxiliary analog to digital converter.
   *
   * \param which_dboard             [0,1] which d'board
   * \param which_adc                [0,1]
   * \param value                    return 12-bit value [0,4095]
   * \returns true iff successful
   */
  bool read_aux_adc (int which_dboard, int which_adc, int *value);

  /*!
   * \brief Read auxiliary analog to digital converter.
   *
   * \param which_dboard         [0,1] which d'board
   * \param which_adc            [0,1]
   * \returns value in the range [0,4095] if successful, else READ_FAILED.
   */
  int read_aux_adc (int which_dboard, int which_adc);

The second version has a python binding:

  v = u.read_aux_adc(0, 0)

where u is an instance of a usrp.source_c or usrp.sink_c

> Do we have something like that?? I have a 1K/sec signal I need to
> look at. has anybody else used these inputs to bypass and go
> directly to the ADC??  

The bad news is that these are read asynchronously using a slow path
over the USB. You probably can't read them fast enough to sample to
your 1K/sec signal, and the sampling is asynchronous.

Eric