How can we display a 2 digit output on a 7 segment display ?

Displaying a 2-digit output on a 7-segment display involves driving each segment of each digit independently. Each digit is represented by a separate set of 7 LEDs (segments). Here’s a detailed explanation of how to achieve this using a microcontroller, specifically considering the common cathode 7-segment display type:

Components Needed:

Common cathode 7-segment displays (2 digits)
Microcontroller (e.g., Arduino)
Resistors
Jumper wires

Steps:

1. Identify the Pins:

Common Cathode Display: Identify the common cathode pin for each digit. Common cathode displays have one pin shared among all cathodes.
Segment Pins: Identify the pins corresponding to each LED segment for each digit.

2. Connect Display to Microcontroller:

Common Cathode Connection:
- Connect the common cathode pin of the first digit to a digital pin on the microcontroller.
- Connect the common cathode pin of the second digit to another digital pin on the microcontroller.
Segment Connections:
- Connect the segment pins of both digits to different digital pins on the microcontroller. Ensure that corresponding segments are connected to the same pin for both digits.

3. Write a Program:

Segment Mapping: Create a mapping of segments to the corresponding digital pins on the microcontroller. For example:css
const int segments[] = {A, B, C, D, E, F, G};
Digit Selection: Define which digit to display by setting the common cathode pins LOW. Activate one digit at a time while displaying the corresponding segments.cpp
digitalWrite(commonCathodeDigit1, LOW); // Activate digit 1 digitalWrite(commonCathodeDigit2, HIGH); // Deactivate digit 2

4. Multiplexing:

Iterate Through Digits:
- Use a loop to iterate through each digit and display the desired numbers.
- For each digit, set the common cathode pin LOW to activate it and display the corresponding segments for the number to be shown.
Delay:
- Introduce a small delay between switching digits to create the illusion of both digits being displayed simultaneously.
cpp
delay(5);

5. Display Numbers:

Segment Activation:
- Activate the specific segments to display the desired numbers. Use the segment mapping created earlier.
cpp
digitalWrite(segments[0], HIGH); // Display segment A digitalWrite(segments[1], HIGH); // Display segment B // … Continue for all segments
Digit 1 Example:
cpp
digitalWrite(commonCathodeDigit1, LOW); // Activate digit 1 digitalWrite(commonCathodeDigit2, HIGH); // Deactivate digit 2 // Display number 5 on digit 1 digitalWrite(segments[0], HIGH); // Display segment A digitalWrite(segments[1], LOW); // Display segment B // … Continue for other segments delay(5); // Introduce delay
Digit 2 Example:
cpp
digitalWrite(commonCathodeDigit1, HIGH); // Deactivate digit 1 digitalWrite(commonCathodeDigit2, LOW); // Activate digit 2 // Display number 3 on digit 2 digitalWrite(segments[0], HIGH); // Display segment A digitalWrite(segments[1], HIGH); // Display segment B // … Continue for other segments delay(5); // Introduce delay

6. Repeat:

Repeat the Process:
- Continuously loop through the digits, displaying the desired numbers on each.

Considerations:

Ensure that the common cathode pins are properly controlled to select the digit you want to display.
Adjust the delay value based on your specific requirements and the persistence of vision to create a stable display.

Extensions:

You can further enhance the display by incorporating additional features like dimming, scrolling, or displaying other characters.

Professional Assistance:

If working with complex circuits or larger displays, consider consulting with experienced electronics professionals or engineers for optimal results.

In summary, displaying a 2-digit output on a 7-segment display involves multiplexing the digits and controlling the segments through a microcontroller. By selectively activating segments for each digit in a loop, you can create the appearance of a continuous display of two digits.