Electronics > Projects, Designs, and Technical Stuff
ADC reading high when sampling too fast
T3sl4co1l:
Yes, that would do, or there may be a GND setting in the mux. Could also repeat the measurement on a given channel (rather than scanning between inputs, as I assume is being done?).
Overclocking ADC tends to skew or destroy LSBs, so it's not a great idea in general. Would be interesting to see if some parts can be overclocked without errors, even at min/max Vdd and temp. I would guess so. Not at all useful for production of course, more of a neat curiosity.
Tim
magic:
--- Quote from: T3sl4co1l on July 08, 2020, 11:03:46 pm ---Not at all useful for production of course, more of a neat curiosity.
--- End quote ---
Budget scope vendors would like a word with you :)
T3sl4co1l:
Well, budget is a relative thing... if you can get Chinese peasants sorting your MCUs for pennies, maybe it's worthwhile. ::)
Tim
RoGeorge:
--- Quote from: danie1 on June 24, 2020, 06:45:52 pm ---So, the question is, how can an ADC read higher than the highest DC in the system when the sampling period is too short?
I've attached the schematic for the switchable low pass filter for clarity.
--- End quote ---
Resonance maybe? :-//
The schematic only includes the intended components. Apart from those, there is parasitic inductance, stray capacitance, reflections on impedance mismatches, and so on.
Another reason might be the switching inside the ADC. When switched too fast, the internal ADC switches might accidentally pump some extra charge into the internal switched capacitors.
T3sl4co1l:
Ah, thank you for proving my point -- in perhaps the bleakest way imaginable. :o
Tim
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