high gain ADC modes
%AAAA_BBBB_FFF_PPPVVV_OHHHLLL_TT_MMMMM_0 %VVV = ADC config 000: GIO, 1x (~5 volt range, centred on VIO/2) 001: VIO, 1x " 010: RevB: PinB, 1x RevC: high-Z 011: PinA, 1x " 100: PinA, 3.16x (~1.58 volt range, centred on VIO/2) 101: PinA, 10x (~0.5 volt range, centred on VIO/2) 110: PinA, 31.6x (~0.158 volt range, centred on VIO/2) 111: PinA, 100x (~0.05 volt range, centred on VIO/2)I just noticed that there are ADC modes with a gain higher than 1x what means they have a smaller input range that doesn't include GND and VCC. What are those modes intended to be used for?
I think they can probably used only for AC signals like microphones or other audio signals because the auto-calibration (GIO/VIO switch) doesn't work for them. I fear that the offset could be larger than the input range (at least for the 31.6x and 100x modes) what would make them completely useless for DC signals. Or can we make assumptions on the ratios of the internal resistors so that it's possible to calibrate at least the offset in 1x mode and then switch to higher gain?
I wonder if this could be used to measure low voltage sensor signals like thermocouples directly.