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Topic: Uno Reference Voltage of 1.1v (Read 3 times) previous topic - next topic

gggggggg

Hello, I am told the Reference Voltage of 1.1v exists on the UNO, but can someone please tell me which pin I need to connect my multi meter to, to read it.

thanks



gggggggg

Follow up question:  if my voltage is 1.071, and the system is expecting 1.1, does that mean I can hook up the Positive of my battery power source to A1, read the value, and get 97.36363636363636% of that value as the current voltage in my battery source?

Or would I need to get 102.7077497665733%  of it, to get the current battery source voltage.

2.7% is a fair amount to be out.  Aside from the above example, where else would you use a value like this?  I have a triply axis gyro/accel/temp in my project (connected to A4 and A5  - https://www.sparkfun.com/products/11028) does that mean I should expect my results there are 2.7% out also?

Or is it even more complex than that, and I have to apply the 2.7% to the current battery volt.  Check that against 5v (or 3.3v), and use that new ratio or 'something' against my values based on if my module is using 3.3v or 5v source from the arduino.

mauried

Its important to read the spec sheet for the Atmega328 when looking at the internal voltage referance specs.
The 1.1 volt referance can vary anywhere between 1.0 to 1.2 volts, which is 20% variation.
Its not a stabilised voltage referance.
If you want a stabilised referance voltage for things like calibrating voltmeters, then you need something like this.
http://www.analog.com/en/special-linear-functions/voltage-references/adr4525/products/product.html
Voltage guaranteed to be stable within 0.02%.
They aint cheap though.


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