Arduino Programming Essentials: Logic & Control Flow

Posted on Sep 27, 2025 in Computers

Digital Read Serial Example

This section presents an Arduino sketch demonstrating how to read a digital input and print its state to the Serial Monitor.


/*
  Leen - Digital Read Serial - May 13
  DigitalReadSerial

  Reads a digital input on pin 2, prints the result to the Serial Monitor

  This example code is in the public domain.

  https://www.arduino.cc/en/Tutorial/BuiltInExamples/DigitalReadSerial
*/
// digital pin 2 has a pushbutton attached to it. Give it a name:
int pushButton = 4;

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  // make the pushbutton's pin an input:
  pinMode(pushButton, INPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input pin:
  int buttonState = digitalRead(pushButton);
  // print out the state of the button:
  Serial.println(buttonState);
  delay(1);   // delay in between reads for stability
}

RGB LED Dimmer Sketch (Placeholder)

This section is intended for an RGB LED dimmer sketch. The provided code is a duplicate of the Digital Read Serial example. Please replace it with the correct RGB LED dimmer code for proper functionality.


/*
  Leen - Digital Read Serial - May 13
  DigitalReadSerial

  Reads a digital input on pin 2, prints the result to the Serial Monitor

  This example code is in the public domain.

  https://www.arduino.cc/en/Tutorial/BuiltInExamples/DigitalReadSerial
*/
// digital pin 2 has a pushbutton attached to it. Give it a name:
int pushButton = 4;

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  // make the pushbutton's pin an input:
  pinMode(pushButton, INPUT);
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input pin:
  int buttonState = digitalRead(pushButton);
  // print out the state of the button:
  Serial.println(buttonState);
  delay(1);   // delay in between reads for stability
}

Arduino Boolean Logic: TRUE and FALSE

In Arduino programming, the numbers 0 and 1 are directly connected to the boolean terms TRUE and FALSE:

  • TRUE is represented by 1.
  • FALSE is represented by 0.

Specifically, in logical operations, 1 signifies “true” and 0 signifies “false”.

Logical Operators: OR (||) vs. AND (&&)

Understanding the difference between logical OR and AND operators is crucial for conditional logic:

  • OR (||): Returns TRUE (1) if at least one condition is true.
  • AND (&&): Returns TRUE (1) only if both conditions are true.

The Equality Operator (==) in Arduino

The == command is used to check for equality between two values:

  • a == b checks if the value of a is equal to the value of b.
  • If they are equal, it returns TRUE (1); otherwise, it returns FALSE (0).

Main Relational Operators in Arduino

Relational operators are used to compare two values. The primary relational operators include:

  • == (equal to)
  • != (not equal to)
  • < (less than)
  • > (greater than)
  • <= (less than or equal to)
  • >= (greater than or equal to)

Return Values of Relational Operators

Relational operators return an integer value representing a boolean state:

  • 1 for TRUE
  • 0 for FALSE

Conditional Statements in Flowcharts

In flowcharts, conditional statements are visually represented as diamonds. Inside the diamond, a decision is made (e.g., “Is one number less than another?”). Based on the result (TRUE or FALSE), different actions or paths are executed within the program flow.

Program Command Execution Order in Arduino

Commands in an Arduino program execute sequentially. This means that each command runs one at a time, in the exact order they are written from top to bottom within the sketch.

Control Flow Commands: Purpose and Function

Control Flow commands, such as loops (e.g., for, while) and if statements, dictate the order in which different parts of the program run. They enable functionalities like repeating actions multiple times or choosing different execution paths based on specific conditions.

Pseudocode vs. Flowchart: Key Differences

Both pseudocode and flowcharts are tools for planning program logic, but they differ in their representation:

  • Pseudocode: A written description of what a program does, expressed in plain, human-readable language, resembling code but without strict syntax rules.
  • Flowchart: A visual diagram that uses standard symbols to illustrate the steps, decisions, and overall flow of a program.

Purpose of Semicolons in Arduino Sketches

In Arduino (C/C++ based) code, semicolons (;) are essential. They act as statement terminators, indicating to the compiler that a command or instruction is complete. Every statement in an Arduino sketch must end with a semicolon.