Functions

In Arduino, functions are blocks of code that perform a specific task. They help organize your code, make it reusable, and improve readability.

Key aspects of Arduino functions:

• Purpose: Functions encapsulate a series of instructions, performing a defined action. This makes complex programs easier to manage.

• Structure: A function has a name, optionally takes inputs (arguments), and may return a value. The general structure is:

  returnType functionName(parameter1Type parameter1Name, parameter2Type parameter2Name, ...) {
    // Code to be executed
    return returnValue; // If returnType is not void
  }
  

• Return Type: Specifies the data type of the value the function returns (e.g., int, float, void). void means the function doesn't return any value.

• Name: A unique identifier for the function. Choose descriptive names.

• Parameters/Arguments: Input values passed to the function. Defined by their data type and name. A function can have zero or more parameters.

• Body: The code block enclosed in curly braces {} that contains the instructions the function executes.

• Return Statement: Used to send a value back to the part of the code that called the function (if the return type is not void).

Examples:

1. Function to blink an LED:

   void blinkLed(int pin, int delayTime) {
     digitalWrite(pin, HIGH);
     delay(delayTime);
     digitalWrite(pin, LOW);
     delay(delayTime);
   }
   
   void setup() {
     pinMode(13, OUTPUT); // LED on pin 13
   }
   
   void loop() {
     blinkLed(13, 500); // Blink LED on pin 13 with 500ms delay
   }
   

   • blinkLed is the function name.
   • void indicates it doesn't return a value.
   • It takes two integer parameters: pin (the LED pin number) and delayTime (the delay in milliseconds).
   • The loop function calls blinkLed with specific values (pin 13, delay 500ms).

2. Function to calculate the sum of two numbers:

   int add(int a, int b) {
     int sum = a + b;
     return sum;
   }
   
   void setup() {
     Serial.begin(9600);
   }
   
   void loop() {
     int result = add(5, 3); // Call the add function
     Serial.print("Sum: ");
     Serial.println(result); // Print the result to the Serial Monitor
     delay(1000);
   }
   

   • add is the function name.
   • int indicates it returns an integer value.
   • It takes two integer parameters: a and b.
   • The loop function calls add with values 5 and 3, storing the returned sum in the result variable.

Benefits of using functions:

• Code Reusability: Write code once and use it multiple times.

• Organization: Break down complex tasks into smaller, manageable functions.

• Readability: Easier to understand code when it's divided into logical blocks.

• Maintainability: Easier to modify and debug code when it's well-structured.

In summary, functions are essential building blocks for Arduino programming, providing a way to structure, organize, and reuse code effectively.