TM1637 4-Digit 7-Segment Clock Display

Drive four bright 7-segment digits with just two MCU pins thanks to the TM1637 — the same chip behind dollar-store digital clocks, scoreboards, and timer modules.

Difficulty: Breadboard. Estimated build time: about 25 minutes. Estimated parts cost: about US$4.50. 4-part bill of materials with live supplier pricing. A 4-digit numeric display that reads anything from a clock (with the famous flashing colon) to a temperature, lap counter, voltage reading, or score tally — and only costs two GPIO pins on your MCU.