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Topic: Using AREF pin to focus range: will this break my board? (Read 79 times) previous topic - next topic


Hi all,
Will this break my arduino?

I'm using an analog accelerometer which sends readings from 0-5V, and I have an arduino uno, which has a default 5V reference voltage - so far so good. However, for my particular application all the data is between 1-3V. I want to set the AREF pin to 3.3V so I get better resolution in my readings (i.e. 3.3/1024 volts per unit instead of 5/1024). However, I have one concern: will it break anything if by some accident the sensor sends a reading of, for example, 4V when I have the board set to a 3.3V reference voltage?

Thank you!


No, inputs > AREF (and <= 5 V) convert to 1023.
Consult the ATmegaxx8 data sheet and https://www.arduino.cc/en/Reference/AnalogReference


A warning from the analogReference reference page:

If you're using an external reference on the AREF pin, you must set the analog reference to EXTERNAL before calling analogRead(). Otherwise, you will short together the active reference voltage (internally generated) and the AREF pin, possibly damaging the microcontroller on your Arduino board.

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