| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 | input +------>-------|+ \ |
| 12 | | \ |
| 13 | .-------. | }---. |
| 14 | | | | / | |
| 15 | | dac|-->--|- / | |
| 16 | | | |_/ | |
| 17 | | | | |
| 18 | | | | |
| 19 | | irq|------<-------' |
| 20 | | | |
| 21 | '-------' |
| 22 | The boolean invert attribute (0/1) should be set when the |
| 23 | input signal is centered around the maximum value of the |
| 24 | dac instead of zero. The envelope detector will search |
| 25 | from below in this case and will also invert the result. |
| 26 | The edge/level of the interrupt is also switched to its |
| 27 | opposite value. |
| 28 | |
| 29 | What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_compare_interval |
| 30 | Date: October 2016 |
| 31 | KernelVersion: 4.9 |
| 32 | Contact: Peter Rosin <peda@axentia.se> |
| 33 | Description: |
| 34 | Number of milliseconds to wait for the comparator in each |
| 35 | step of the binary search for the input peak level. Needs |
| 36 | to relate to the frequency of the input signal. |