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Al Williams

Dr. Dobb's Bloggers

Intermediate User Interfaces for Embedded Systems

December 06, 2010

I tend to classify my designs by two criteria: the time response required and also the user interface required. Some of my designs have no user interface. A few have buttons and LEDs. Some have the usual LCD display with a few buttons or maybe a keypad. And still others have full-blown touchscreens.

It has always struck me that there's a pretty big gap between a text-only LCD and a few menu buttons and a full VGA display running Linux.

I haven't tried them yet, but buttons with built in LCD displays caught my eye today. Maybe that would fill the gap I've notice.

These aren't dirt cheap (a little more than US$30 each in singles) but the specifications sound good. Each switch has 64x32 pixel graphical LCD and an RGB backlight can produce over 10,000 colors. The switches initialize themselves so you only need to send data to them if you want them to change appearance. An SPI interface lets you program it via two of the six terminals (power, ground, SPI, and -- oh yeah -- the actual switch closure.

The RGB backlight makes these unsuitable for low power use. With a single LED on, consumption is about 25mA and if you get fancy that can go up to 60mA.

These look like they'd make a pretty futuristic looking front panel.

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