Programming: ADC (Analog to Digital Converter) Setting the Internal Voltage of 2.56v as the Voltage Reference

The AVR microcontroller offers an internal voltage reference of 2.56v to be used if so desired. If the device that is being measured by the ADC has a top value of 2.56v then this option would be a good one. The accelerometer that I am connecting to the ADC actually has a higher top voltage, but not that much more, so I selected this option. The register that this option can be controlled is the ADMUX register. The REFS1 and REFS0 control the source of the reference voltage. In this case, to select the internal 2.56 volts as the reference, both REFS1 and REFS0 must be set.