Basics of ADC values and Voltages

In this post you'll learn the relationship between adc values and voltages. After going through this post you'll be able to learn the relationship between  voltages that are going in to the Arduino.

Things you should know:
  1. Resolution of your ADC (in bits)
  2. System voltages
  3. ADC reading
  4. Measured voltages

Resolution of ADC

The resolution in expressed in bits. For calculations you need to convert the bits to actual number. Lets say your Arduino board has 10 bits. Now you can calculate the resolution by using formula  2n-1 Here 210 -1 = 1024 - 1 = 1023. It is 1023 because the counting starts from 0.

System voltages (Input Voltages)

These are the voltages which you are taking in the system. Lets say you are using an input 5 V on the voltage divider.

ADC reading

The reading which ADC is being displayed.

Measured voltages

These are the actual voltages measured by the ADC.

The relationship between all terms:
Lets say your adc is displaying 256 and it is 10 bit adc, then resolution be 1023 and systems voltages be 5. Then the analog voltages are 1.25. 

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