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