In a recent blog post on omzlo.com, [Alain] explains how they found a bug in the Arduino SAMD21 analogRead() code which causes the output to be offset by between 25 mV and 57 mV. For a 12-bit ADC ...

While we have seen other Arduino based constant loads before, [Jasper’s] is very simple and straight forward compartively. [Jasper] also includes both the schematic and Arduino code ...