Arduino Due Reference Voltage

Official Hardware Mega Due
1

Hello,

I am looking to use the Arduino Due to take accurate analog measurements. I have two questions regarding the reference voltage used to read the analog pins against:

  1. Does the Arduino Due allow an external voltage reference? This link:

says that the Due does not have that capability, but from what I can tell the Due has a “AREF” pin on it. I don’t know why it would have that pin if it didn’t have that capability.

  1. What is the accuracy of the internal voltage reference on the Due? I think I remember reading it was 1% but I can’t find a source for that information.

Thank you.

2

Edit: I meant “default” voltage, rather than “internal”.

3

This thread answers your question

https://forum.arduino.cc/index.php?topic=371200.0

This Application Note from Silicon Labs might be of interest if you want more than 12-bit resolution with your builtin ADCs:

And an Application Note from Atmel for ADC calibration, necessary for an improved accuracy :

One good trick with the ADC is to have one input dedicated as a purging input for a better accuracy. Connect it to ground through a small resistor (say 100 ohms) and sample that channel in between each channel you are interested in. This ensures that the S&H capacitor is purged of residual charge between readings. The resistor is important to reduce current flow, but you want it small enough that the capacitor discharges in a reasonable time.