七段顯示器是用來顯示數字的常用電子元件，在很多地方都可以看到它的身影，例如電子時鐘、溫度顯示器和各種儀表 七段顯示器分成共陽極和共陰極兩種，不管是哪一種，內部構造都是由 8 個 LED 發光二極體所組成，其中七個是筆劃，另外一個是小數點，如下圖所示，依順時針方向分別為 a, b, c, d, e, f, g 以及小數點 dp (decimal point)(Raspberry Pi A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.
Seven-segment displays are widely used in digital clocks, electronic meters, basic calculators, and other electronic devices that display numerical information)