Virtual IoT Lab DEI

Instructions

Objective:

Learn how to control a 7-segment display to show digits (0-9) using Arduino digital outputs.

Steps to Perform:

Click "Start Simulation" to power up the Arduino circuit
The 7-segment display will automatically start counting from 0 to 9
Observe how different segments light up to form each digit
Watch the decimal point blink after each number
The counter will loop back to 0 after reaching 9

Key Concepts:

7-Segment Display: LED display with 7 segments (A-G) plus decimal point
Common Cathode: All segment cathodes connected together to ground
Digital Output: Arduino controls each segment individually (HIGH/LOW)
Segment Mapping: Different combinations create digits 0-9
Pin Control: Uses pins 4-12 for segments and common cathode

Arduino Code - main.ino

            #define COMMON_A        12
#define SEGMENT_A       11
#define SEGMENT_B       10
#define SEGMENT_C        9
#define SEGMENT_D        8
#define SEGMENT_E        7
#define SEGMENT_F        6
#define SEGMENT_G        5
#define DECIMAL_POINT   4

// Code for COMMON CATHODE 7-SEGMENT DISPLAY

int i = 0;
int num = 0;

// Pin list (4–12)
int pinList[9] = {
  DECIMAL_POINT,
  SEGMENT_G,
  SEGMENT_F,
  SEGMENT_E,
  SEGMENT_D,
  SEGMENT_C,
  SEGMENT_B,
  SEGMENT_A,
  COMMON_A
};

void setup() {
  for (i = 0; i <= 8; i++) {
    pinMode(pinList[i], OUTPUT);
  }
}

void loop() {

  digitalWrite(COMMON_A, LOW);

  if (num == 10)
    num = 0;

  switch (num) {

    // Display 0
    case 0:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      digitalWrite(SEGMENT_E, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      break;

    // Display 1
    case 1:
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      break;

    // Display 2
    case 2:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      digitalWrite(SEGMENT_E, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      break;

    // Display 3
    case 3:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      break;

    // Display 4
    case 4:
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      break;

    // Display 5
    case 5:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      break;

    // Display 6
    case 6:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      digitalWrite(SEGMENT_E, HIGH);
      break;

    // Display 7
    case 7:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      break;

    // Display 8
    case 8:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      digitalWrite(SEGMENT_E, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      break;

    // Display 9
    case 9:
      digitalWrite(SEGMENT_A, HIGH);
      digitalWrite(SEGMENT_B, HIGH);
      digitalWrite(SEGMENT_C, HIGH);
      digitalWrite(SEGMENT_D, HIGH);
      digitalWrite(SEGMENT_F, HIGH);
      digitalWrite(SEGMENT_G, HIGH);
      break;

    // Error case: blink all segments
    default:
      for (i = 1; i < 8; i++)
        digitalWrite(pinList[i], HIGH);

      delay(1000);

      for (i = 1; i < 8; i++)
        digitalWrite(pinList[i], LOW);

      delay(1000);
      break;
  }

  // Increment number
  num++;

  delay(1000);

  // Clear segments
  for (i = 1; i < 8; i++)
    digitalWrite(pinList[i], LOW);

  delay(1000);

  // Decimal point blink
  digitalWrite(DECIMAL_POINT, HIGH);
  delay(1000);
  digitalWrite(DECIMAL_POINT, LOW);
}

          