Internal Ref and 5 volts


I am building a project which involves a LM37 temperature sensor and therefore using the internal reference 1.1 volts. However, I also have a potentiometer from which I am reading the voltage from the wiper. The outer arms of the pot are connected between gnd and 5 volts. This results in only a fraction of the pot being useable. Is there a 1.1volt reference available for me to use on the Uno. Other than that, how could I get around the issue?

Grateful for any assistance.

You can put a resistor in series with the pot to make a [u]voltage divider[/u].* For example with a 10K pot as the "bottom" resistor and 40K** resistor as the "top-resistor", you'd have 1/5 voltage divider with 1V at the "top" of the pot.

  • A pot is a variable voltage divider.

** 40K is not a standard resistor value, it just makes an easy example for calculations.

You can also cause your program to switch between the internal 1.1v ref and the 5v reference for the different measurements. It would be wise to read the Atmega 328 datasheet to check if there are any timing limitations associated with switching - to allow the reference to settle.