Simple Display Solution

Need a simple display for an upcoming design? Check out this easy-to-replicate solution. Devlin presents a simple microcontroller-based circuit to animate a four-digit, seven-segment LED. Inexpensive seven-segment, light-emitting diode (LED) displays were designed to represent the numbers zero through nine, but they occasionally are used to show the additional hexadecimal characters A through F. While it takes 14 segments to display the entire alphabet, you can easily display short messages on a seven-segment display. In this article, I’ll explain how I designed a simple circuit that uses an inexpensive Microchip Technology PIC16F630 microcontroller and a few other parts to animate text on a four-digit, seven-segment LED display (see Photo 1 and Photo 2). Photo 1Photo 2 Photo 1 This is a top view of the animated ornament with an escutcheon mounted to hide the circuitry. The escutcheon can be painted green to blend in with holiday greenery. Photo 2a—This is the component side of the circuit board. The display is mounted on the foil side. b—This is a detailed view of the display mounting using single row sockets. The display can be soldered directly to the board, or a standard DIP socket can be cut apart to make a connector. SEVEN SEGMENTS Graphic displays have become ubiquitous in electronic devices, since their cost has continued to decline, but seven-segment displays are still used in many applications. While it's now common to see seven-segment displays implemented using liquid crystal technology, LEDs are more appealing in applications such as digital clocks or when a readable display is needed in a dark room. The original purpose of seven-segment displays was to indicate the decimal digits 0–9, and they do this quite well. Early computer development boards extended the seven-segment character set to the hexadecimal realm by adding the letters A–F, albeit in a functional, rather than aesthetic, fashion (see Fi