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+What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_invert
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ The DAC is used to find the peak level of an alternating
+ voltage input signal by a binary search using the output
+ of a comparator wired to an interrupt pin. Like so:
+ _
+ | \
+ input +------>-------|+ \
+ | \
+ .-------. | }---.
+ | | | / |
+ | dac|-->--|- / |
+ | | |_/ |
+ | | |
+ | | |
+ | irq|------<-------'
+ | |
+ '-------'
+ The boolean invert attribute (0/1) should be set when the
+ input signal is centered around the maximum value of the
+ dac instead of zero. The envelope detector will search
+ from below in this case and will also invert the result.
+ The edge/level of the interrupt is also switched to its
+ opposite value.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_compare_interval
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ Number of milliseconds to wait for the comparator in each
+ step of the binary search for the input peak level. Needs
+ to relate to the frequency of the input signal.