Ed Ifd 2 Promo 5eea4619968dd

SPI Eases Interfacing For 5-By-5 Dot-Matrix Display

March 21, 2013
The circuit interfaces a display that features four 5-by-5 dot-matrix characters by using the display’s serial peripheral interface and a programmable system on a chip (PSoC). The SPI reduces firmware overhead and enhances clock stability.

Download this article in .PDF format
This file type includes high resolution graphics and schematics.

When discussing displays, seven-segment displays and LCDs are among the first that come to mind. Each type has its pros and cons. But generally, seven-segment displays cannot display letters, and LCDs tend to be bulky. Recently, I came across a four-character 5-by-5 dot-matrix, serial-input display (the SCDV5542 from Osram) that has several advantages.

The display can display alphanumeric characters and measures 10.16 by 19.91 mm (0.400 by 0.784 in.) with 3.12-mm (0.123-in.) characters. It has a serial peripheral interface (SPI) and allows high-speed data input. It features eight levels of dimming, an internal/external clock capability, and decoders, multiplexers, and an LED driver.

The device consists of a CMOS IC with control logic and drivers for the four 5-by-5 characters (Fig. 1). Each individual LED dot is addressable, so the user can create special characters. The device requires only four lines from a microcontroller. The IC accepts decoded serial data that is stored in internal RAM. Asynchronously, the RAM is read by the character multiplexer at the rate defined by the strobe.

Download this article in .PDF format
This file type includes high resolution graphics and schematics.
Download this article in .PDF format
This file type includes high resolution graphics and schematics.

About the Author

Girish Choudankar

Girish Choudankar works at Emphatec Inc., a Toronto-based design house for industrial control interfaces and switch-mode power supplies. He holds a bachelor's degree in electronics engineering from Mumbai University, India. 

Sponsored Recommendations

Comments

To join the conversation, and become an exclusive member of Electronic Design, create an account today!