7 Segment Display
A 7-segment display is an electronic display device that employs 7 LEDs (Light Emitting Diodes) placed in a certain arrangement to show numerals and characters by lighting up various combinations of segments.
Types of Seven Segment Display
There are two types of seven segment displays
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Common Anode Display
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Common Cathode Display
1). Common Anode Display
In a common anode display, all of the anode terminals from eight light emitting diodes are connected to a 5 volt power source.
In normal conditions, our microcontroller sends logic high to each segment. As a result, each section either stays off (or) does not illuminate.
Similarly, when we wish to turn on a certain LED in a seven-segment display, we send a logic low signal.
Because an LED illuminates only when there is a logic high signal on the anode side and a logic low signal on the cathode side, as is the case with a common anode type display.
2). Common Cathode Display
In a common cathode segment display, the cathodes of all eight light emitting diodes are connected to the ground.
To switch off any of the seven segments, we apply logic low from the microcontroller to that section.
Similarly, to turn on a particular LED in a seven-segment device, we send a logic high signal from the microcontroller’s digital output pin.
Because an LED illuminates only when there is a logic high signal on the anode side and a logic low signal on the cathode side, as is the case with a common cathode type display.