A seven-segment display is an electronic display device using 7 LEDs segments arranged in a configuration to show digits/characters, by selectively activating different combinations of these segments to form the desired number or character.
segment: part, section
7 LED segments are labeled from the letter 'a' to 'g' put in the shape of number 8. Each “segmented” LED is made of a greater/lesser amount of semi-conductor components, emitting light due to current going through them and of light-scattering material (primarily milky in color) to ensure illumination uniformity.
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The diodes connect in 2 ways--configuration by common anode or common cathode.
Displays by a common anode have all positive leads of LED segments connect at 1 point. D
Displays by common cathode have 1 lead for all negative lines.
2 of most used coding methods are BCD (binary coded decimal) coding and hexadecimal coding . Besides this, the meaning of the dot on 7-segment displays is another crucial part of precise data display.
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BCD coding assigns a unique binary code (often 4-bits) to each digit from 0 to 9 and certain alphanumeric characters, like letters from A to F. All binary code relates to a certain set of LED segments, which is activated to show a digit/character.
Supply voltage To calculate a 7-segment display's resistor values, know its supply voltage, the LEDs' forward voltage, and the desired current, via electrical principles like Ohm's law to use to find the resistance to limit current.
Barrier voltage
[Q1] E.g. If a source voltage is 5V and the barrier voltage is 2.3 V, find the current value limiting the resistor to limit 25 mA current.
5 V - 2.3 V = 2.7 V
25 mA = 0.025 A
R = V÷R = 2.7V ÷ 0.025A = 108 Ω can limit 25 mA.
[2] Besides 7-segment, more number of segments (8, 9, 14, 16, and even 22-segment) exist. Advanced designs show new possibilities to show characters and are used in certain usages via more flexibility and precision. We gain even greater possibilities by using LED panels allowing for the display of simple graphics.
[2] a 16-segments display
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[1.2] Calculator spelling
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