1b475f80bSPeter RosinWhat: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_invert 2b475f80bSPeter RosinDate: October 2016 3b475f80bSPeter RosinKernelVersion: 4.9 4b475f80bSPeter RosinContact: Peter Rosin <peda@axentia.se> 5b475f80bSPeter RosinDescription: 6b475f80bSPeter Rosin The DAC is used to find the peak level of an alternating 7b475f80bSPeter Rosin voltage input signal by a binary search using the output 8*34433332SMauro Carvalho Chehab of a comparator wired to an interrupt pin. Like so:: 9*34433332SMauro Carvalho Chehab 10b475f80bSPeter Rosin _ 11b475f80bSPeter Rosin | \ 12b475f80bSPeter Rosin input +------>-------|+ \ 13b475f80bSPeter Rosin | \ 14b475f80bSPeter Rosin .-------. | }---. 15b475f80bSPeter Rosin | | | / | 16b475f80bSPeter Rosin | dac|-->--|- / | 17b475f80bSPeter Rosin | | |_/ | 18b475f80bSPeter Rosin | | | 19b475f80bSPeter Rosin | | | 20b475f80bSPeter Rosin | irq|------<-------' 21b475f80bSPeter Rosin | | 22b475f80bSPeter Rosin '-------' 23*34433332SMauro Carvalho Chehab 24b475f80bSPeter Rosin The boolean invert attribute (0/1) should be set when the 25b475f80bSPeter Rosin input signal is centered around the maximum value of the 26b475f80bSPeter Rosin dac instead of zero. The envelope detector will search 27b475f80bSPeter Rosin from below in this case and will also invert the result. 28*34433332SMauro Carvalho Chehab 29b475f80bSPeter Rosin The edge/level of the interrupt is also switched to its 30b475f80bSPeter Rosin opposite value. 31b475f80bSPeter Rosin 32b475f80bSPeter RosinWhat: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_compare_interval 33b475f80bSPeter RosinDate: October 2016 34b475f80bSPeter RosinKernelVersion: 4.9 35b475f80bSPeter RosinContact: Peter Rosin <peda@axentia.se> 36b475f80bSPeter RosinDescription: 37b475f80bSPeter Rosin Number of milliseconds to wait for the comparator in each 38b475f80bSPeter Rosin step of the binary search for the input peak level. Needs 39b475f80bSPeter Rosin to relate to the frequency of the input signal. 40