Sensing the analog world

In the Electronics crash course we talked about alternating current vs. direct current and also introduced the potentiometer, a variable resistor. Remember that according to Ohm's law, resistance is proportionate to voltage.

Analog Inputs

To sense a gradually changing electrical signal, we'll use Arduino's analog inputs, located on the left side of the board. These special pins are connected to the Arduino's analog to digital converter (ADC), equipped to convert an analog signal between 0V and 5V into a range of numbers from 0-1023 (zero counts as a value). 

Now upload the following code to the Arduino:

int potPin = 0;
 
void setup() 
{
  Serial.begin(9600);
}
 
void loop() 
{
  int reading  = analogRead(potPin);
  Serial.println(reading);
  delay(500);
}

Turn the knob on the variable resistor and you will see the number change between 0 and 1023.

The Serial Monitor is displaying the analog reading value from A0 using the line:

  int reading  = analogRead(potPin);