1*33ec3e5fSMarius CristeaWhat: /sys/bus/iio/devices/iio:deviceX/boost_current_gain 2*33ec3e5fSMarius CristeaKernelVersion: 6.4 3*33ec3e5fSMarius CristeaContact: linux-iio@vger.kernel.org 4*33ec3e5fSMarius CristeaDescription: 5*33ec3e5fSMarius Cristea This attribute is used to set the gain of the biasing current 6*33ec3e5fSMarius Cristea circuit of the Delta-Sigma modulator. The different BOOST 7*33ec3e5fSMarius Cristea settings are applied to the entire modulator circuit, including 8*33ec3e5fSMarius Cristea the voltage reference buffers. 9*33ec3e5fSMarius Cristea 10*33ec3e5fSMarius CristeaWhat: /sys/bus/iio/devices/iio:deviceX/boost_current_gain_available 11*33ec3e5fSMarius CristeaKernelVersion: 6.4 12*33ec3e5fSMarius CristeaContact: linux-iio@vger.kernel.org 13*33ec3e5fSMarius CristeaDescription: 14*33ec3e5fSMarius Cristea Reading returns a list with the possible gain values for 15*33ec3e5fSMarius Cristea the current biasing circuit of the Delta-Sigma modulator. 16*33ec3e5fSMarius Cristea 17*33ec3e5fSMarius CristeaWhat: /sys/bus/iio/devices/iio:deviceX/auto_zeroing_mux_enable 18*33ec3e5fSMarius CristeaKernelVersion: 6.4 19*33ec3e5fSMarius CristeaContact: linux-iio@vger.kernel.org 20*33ec3e5fSMarius CristeaDescription: 21*33ec3e5fSMarius Cristea This attribute is used to enable the analog input multiplexer 22*33ec3e5fSMarius Cristea auto-zeroing algorithm (the input multiplexer and the ADC 23*33ec3e5fSMarius Cristea include an offset cancellation algorithm that cancels the offset 24*33ec3e5fSMarius Cristea contribution of the ADC). When the offset cancellation algorithm 25*33ec3e5fSMarius Cristea is enabled, ADC takes two conversions, one with the differential 26*33ec3e5fSMarius Cristea input as VIN+/VIN-, one with VIN+/VIN- inverted. In this case the 27*33ec3e5fSMarius Cristea conversion time is multiplied by two compared to the default 28*33ec3e5fSMarius Cristea case where the algorithm is disabled. This technique allows the 29*33ec3e5fSMarius Cristea cancellation of the ADC offset error and the achievement of 30*33ec3e5fSMarius Cristea ultra-low offset without any digital calibration. The resulting 31*33ec3e5fSMarius Cristea offset is the residue of the difference between the two 32*33ec3e5fSMarius Cristea conversions, which is on the order of magnitude of the noise 33*33ec3e5fSMarius Cristea floor. This offset is effectively canceled at every conversion, 34*33ec3e5fSMarius Cristea so the residual offset error temperature drift is extremely low. 35*33ec3e5fSMarius Cristea Write '1' to enable it, write '0' to disable it. 36*33ec3e5fSMarius Cristea 37*33ec3e5fSMarius CristeaWhat: /sys/bus/iio/devices/iio:deviceX/auto_zeroing_ref_enable 38*33ec3e5fSMarius CristeaKernelVersion: 6.4 39*33ec3e5fSMarius CristeaContact: linux-iio@vger.kernel.org 40*33ec3e5fSMarius CristeaDescription: 41*33ec3e5fSMarius Cristea This attribute is used to enable the chopping algorithm for the 42*33ec3e5fSMarius Cristea internal voltage reference buffer. This setting has no effect 43*33ec3e5fSMarius Cristea when external voltage reference is selected. 44*33ec3e5fSMarius Cristea Internal voltage reference buffer injects a certain quantity of 45*33ec3e5fSMarius Cristea 1/f noise into the system that can be modulated with the 46*33ec3e5fSMarius Cristea incoming input signals and can limit the SNR performance at 47*33ec3e5fSMarius Cristea higher Oversampling Ratio values (over 256). To overcome this 48*33ec3e5fSMarius Cristea limitation, the buffer includes an auto-zeroing algorithm that 49*33ec3e5fSMarius Cristea greatly reduces (cancels out) the 1/f noise and cancels the 50*33ec3e5fSMarius Cristea offset value of the reference buffer. As a result, the SNR of 51*33ec3e5fSMarius Cristea the system is not affected by this 1/f noise component of the 52*33ec3e5fSMarius Cristea reference buffer, even at maximum oversampling ratio values. 53*33ec3e5fSMarius Cristea Write '1' to enable it, write '0' to disable it. 54