Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector

   1 What:           /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_invert
   2 Date:           October 2016
   3 KernelVersion:  4.9
   4 Contact:        Peter Rosin <peda@axentia.se>
   5 Description:
   6                 The DAC is used to find the peak level of an alternating
   7                 voltage input signal by a binary search using the output
   8                 of a comparator wired to an interrupt pin. Like so::
   9
  10                                            _
  11                                           | \
  12                      input +------>-------|+ \
  13                                           |   \
  14                             .-------.     |    }---.
  15                             |       |     |   /    |
  16                             |    dac|-->--|- /     |
  17                             |       |     |_/      |
  18                             |       |              |
  19                             |       |              |
  20                             |    irq|------<-------'
  21                             |       |
  22                             '-------'
  23
  24                 The boolean invert attribute (0/1) should be set when the
  25                 input signal is centered around the maximum value of the
  26                 dac instead of zero. The envelope detector will search
  27                 from below in this case and will also invert the result.
  28
  29                 The edge/level of the interrupt is also switched to its
  30                 opposite value.
  31
  32 What:           /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_compare_interval
  33 Date:           October 2016
  34 KernelVersion:  4.9
  35 Contact:        Peter Rosin <peda@axentia.se>
  36 Description:
  37                 Number of milliseconds to wait for the comparator in each
  38                 step of the binary search for the input peak level. Needs
  39                 to relate to the frequency of the input signal.