4. Analog Read

The Arduino can read the connected analog sensors through the analog pins.

The R3 board contains a multi-channel, 10-bit analog-to-digital converter. This means it maps the input voltage between 0 and the operating voltage (5V or 3.3V) to an integer value between 0 and 1023.

You need the analogRead(pin) function to read the value of the analog pin.

  • analogRead(pin): Read the value from the specified analog pin.



    • pin: the name of the analog input pin to read from (A0 to A5).


    0-1023. Data type: int.

Example of Analog Read

int analogPin = A0; // device connected to analog pin A0
                  // outside leads to ground and +5V
int val = 0;  // variable to store the value read

void setup() {
   Serial.begin(9600);           //  setup serial

void loop() {
   val = analogRead(analogPin);  // read the input pin
   Serial.println(val);          // debug value

Notes and Warnings

  • The analog pins are A0-A5.

  • You don’t need to call pinMode() before calling the analog pin, but if the pin was previously set to OUTPUT, the function analogRead() will not work properly, in which case you need to call pinMode() to set it back to INTPUT.

Related Components

Below are the related components, you can click in to learn how to use them.