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Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector b/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector new file mode 100644 index 000000000000..2071f9bcfaa5 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector @@ -0,0 +1,36 @@ +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. |