7 segment LED Digital Display 4 Digit CC

Features:

• 4-digit 7-segment LED display with bright red illumination
• Common cathode configuration for easy interfacing
• Supports numeric (0–9), hexadecimal (A–F), and basic symbols
• Standard 2.54mm pin spacing compatible with breadboards
• Suitable for direct use with microcontrollers
• Low cost and efficient display solution
• Works with 3.3V to 5V systems
• Widely used in household appliances and embedded systems

Principle of Work:

The display operates by lighting specific LED segments to form numbers or characters. In a common cathode configuration, the selected digit is activated by connecting its cathode to ground, while the required segments are powered by applying a positive voltage.

To display multiple digits, multiplexing is used. The microcontroller rapidly switches between digits, activating one digit at a time while updating the segment data. Due to persistence of vision, all digits appear continuously lit to the human eye.

Pinout:

• Segment Pins (A–G, DP): Control individual LED segments
• Digit Pins (D1–D4): Select active digit (common cathode)
• Common Cathode: Connect to GND

Applications:

1. Digital clocks and timers
2. Temperature and voltage displays
3. Counters and scoreboards
4. Household appliances (microwaves, washing machines, etc.)
5. Embedded system user interfaces
6. Educational and prototyping projects

Circuit:

• Connect segment pins (A–G, DP) to Arduino digital pins through current-limiting resistors
• Connect digit pins (D1–D4) to Arduino digital pins (for multiplexing)
• Connect common cathode pins to GND
• Use transistors if higher current driving is required

Library:

You can control this display using multiplexing code or libraries such as:

• SevSeg Arduino Library

Code:

The code shows the analog value of a sensor connected to the arduino board. The value displayed can range anywhere from 0 to 9999 on a four-digit display. No need for Library

const int sensorPin= 0;//The analog sensor is connected to analog pin 0 of the arduino

//ABCDEFG,dp
const int numeral[10]= {
B11111100, //0
B01100000, //1
B11011010, //2
B11110010, //3
B01100110, //4
B10110110, //5
B00111110, //6
B11100000, //7
B11111110, //8
B11100110, //9
};

//pins for decimal point and each segment
//dp, G, F, E, D, C, B, A
const int segmentPins[]= { 4, 7, 8, 6, 5, 3, 2, 9};

const int numberofDigits=4;

const int digitPins[numberofDigits] = { 10,11,12, 13}; //digits 1, 2, 3, 4

void setup()
{

for (int i=0; i < 8; i++)
pinMode(segmentPins[i], OUTPUT); //set segment and DP pins to output

//sets the digit pins as outputs
for (int i=0; i < numberofDigits; i++)
pinMode(digitPins[i], OUTPUT);
}

void loop()
{
int value= analogRead(sensorPin);
showNumber(value);
}

void showNumber (int number)
{
if (number == 0)
showDigit (0, numberofDigits-1); //display 0 in the rightmost digit
else
{
for (int digit= numberofDigits-1; digit >=0; digit--)
{
if (number > 0)
{
showDigit(number % 10, digit);
number= number/10;
}
}
}
}

//Displays given number on a 7-segment display at the given digit position
void showDigit (int number, int digit)
{
digitalWrite(digitPins[digit], HIGH);
for (int segment= 1; segment < 8; segment++)
{
boolean isBitSet= bitRead(numeral[number], segment);

isBitSet= ! isBitSet; //remove this line if common cathode display
digitalWrite(segmentPins[segment], isBitSet);
}
delay(5);
digitalWrite(digitPins[digit], LOW);
}

Technical Details:

• Model: SR42056
• Display Type: 4-digit 7-segment LED
• Configuration: Common Cathode
• Display Color: Red
• Operating Voltage: 3.3V – 5V
• Dimensions: 42 × 24 × 12 mm
• Temperature Display Range: -9°C to 60°C
• Temperature Calibration Range: -5°C to +5°C

Resources:

• Tutorial