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cdsteinkuehler
The only thing not really working as expected is the thermistor inputs. The signal levels are so low at room temperature with a 1.8V ADC range that the leakage from the protection diodes is causing measurement offsets. I am considering simply removing the protection diodes from the next version (I have already removed them from my prototype), as I'm not sure they really help all that much. The right way to protect the inptus is with a high input impedence insturmentation amplifier, but that costs money and adds complexity. The design still has a 4.7K series resistor to help protect the analog inputs, which probably puts the BeagleBone about even with the Arduino Mega used with the original RAMPS (which had absolutely *NO* analog input protection at all, but the AVR is likely a bit more robust than the AM3358 on the 'Bone).
If you have any strong opinions about keeping or removing the analog input protection, let me know.
What have you done with this in the newer versions of the board? Particularly, I see that a fully assembled v2.2 board is available from pico-systems. What is the state of the thermistor readings at room temperature with this version?