The seven-segment display is one of the oldest and simplest ways to show numbers in electronics, and it's worth understanding its working principle before diving into any project that uses one.
Internal structure
The display contains seven LEDs arranged in a figure-eight pattern, each labeled with a letter from a to g, plus an optional eighth LED representing the decimal point. By lighting different combinations of these LEDs, you can display every digit from 0 to 9 and a few letters like A, B, C, D, E, and F.
Two types: common cathode and common anode
The display comes in two configurations: common cathode, where all cathode pins connect to ground and segments light up when they receive a HIGH signal, and common anode, where all pins connect to 5V and segments light up when they receive a LOW signal. The common-anode type is more widespread since most logic circuits can sink more current through their outputs.
Wiring it up
Wiring requires eight digital Arduino pins (typically pins 2 through 9) to cover the seven segments plus the decimal point, with the common pin (usually pin 3 or 8 on the display) connected to ground or 5V depending on the display type. Protective resistors of about 220Ω prevent damage to each segment, calculated from the typical forward voltage drop and an operating current of roughly 15mA per segment. The ready-made SevSeg library simplifies displaying numbers in code, instead of manually controlling each segment individually.
You can find seven-segment displays of both types at Juthour Tech.
اترك تعليقا