How to convert ADC values to voltage?

Hello Dears,

My concern is about an analog value that you can read from an ADC from any microcontroller.

Example 1: If I want to read the voltage of a pin of my microcontroller, I need to create a variable that will contain a the analog value but this anlog value is not a voltage yet because I need to convert that into voltage in order to get a real value(I guess it is like that).

1st Question : How many numbers have an analog value in that case?

Example 2: An magnetic sensor that reads the speed of the motor generates a frequency signal

1st Question : How many numbers have an analog value in that case?
2nd Question : How to convert that frequency into a real speed value?

I thank you in advance.

Best regards,

An ADC converts analog signals into digital signals. If you are using an n bit ADC on an analog signal with a reference voltage (Vref), then there will be (2^n) - 1 samples. It’s like dividing the overall voltage (Vref) into (2^n) - 1 chunks. So the resolution of one sample from the chunks is given by Va = {(2^n) - 1}/Vref.

Let’s consider an example, Let’s image a sensor which generates a signal with voltage varying between 0V and 3V. So the reference voltage is 3V. In our example, we will use a 10 bit ADC to break the 3V into chunks (samples). Since we are using 10 bit ADC there will be (2^10) -1 samples, which is 1023.

Now we have broken the 3V into 1023 chunks. So what’s the voltage (resolution) of one chunk? The voltage of one chunk will be 3V/1023, which is 0.0029V. In order to get the voltage of the signal at any time, you have to multiply 0.0029 (resolution) by the sample values from the ADC.

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Thanks For the good explaination