Tool saves time in LCD-interface design

April 08, 2002

Santa Clara, CA-First impressions are lasting. Because the user interface is often the suit and tie of an LCD embedded product, ways to efficiently tailor its appearance and behavior are invaluable. Traditionally, implementations of LCD interfaces fall in the embedded code realm. Popular GUI development kits make the coding task less tedious, but usually require some knowledge of complex graphics programming.

To simplify and expedite interface design on medium size LCD displays, Amulet Technologies has developed a novel hardware-based alternative. Easy GUITM uses a patented "m HTML browser" ASIC to reduce embedded graphical interface code to the triviality of an HTML web page.

Amulet's browser chip serves as both LCD controller and user interface engine. The intended architecture has the main embedded application running on a separate processor, communicating with

Easy GUI

via an RS-232 serial interface. This arrangement significantly boosts efficiency by freeing the main microprocessor and memory of any graphics work. An additional benefit is that much of the user interface logic and all of the text and images can be revised or upgraded with no changes to the main embedded device firmware.

The ASIC is available as a component for designers who wish to incorporate the browser technology into their LCD controller designs. The most recent chip and compiler supports monochrome single-scan LCD's up to full VGA resolution (640 x 480 pixels). The 80-pin ASIC requires a 3.3V power supply, serial flash, 64k memory, and a clock (up to 20 MHz). The turnkey kit I tested came with a backlit display, analog touch panel, and a controller. For specialized applications, boards that accommodate other display configurations are available.

Interfaces for the Easy GUI are laid out in the same manner as an HTML website, a strategy clever in several ways. The standard and universal nature of HTML allows GUI prototype screens to be viewed in any web browser. Such accessibility makes the demonstration and testing of new interfaces as simple as visiting a web page. And advanced HTML editors like Macromedia Dreamweaver and Adobe GoLive can now be used to perform LCD interface design.

Using tools included on a CD ROM, I successfully built and deployed a basic touch screen interface. Text, buttons, and images built up quickly as I followed useful examples in the MSWindows-based development kit. I compiled my new interface into native "m HTML" required by the display chip. Voila! In a single button click, my screens were up and running on the LCD display. The PC's standard 9 pin DIN "COM" port communicated over the supplied cable without a hitch.

The Easy GUI compiler is competent in handling GIF and JPEG monochrome images as well as most HTML presentation tags. To achieve "flipbook" style animation for screen components, animated GIF images are rendered in motion and include speed control. A suite of scaleable proprietary "widgets" provides interface elements lacking in HTML, such as bar graphs, line plots, and sliders.

I did discover some limitations on what the compiler can parse: It lacks support for frames, image scaling, or "text wrap" around images. Tables can be used for alignment purposes only (no visible borders drawn). Only one font can be displayed: a sans serif typestyle rendered in five different sizes with bold, italic, and underline as options.

Once an interface is compiled, uploaded, and running on the GUI controller, communication with the main process occurs over the serial port. Special codes embedded in the HTML invoke "widgets" to send and receive messages. Using this technique, a timer or user input from the touch panel initiates events. The Easy GUI client acts as master and can send five different types of messages including "get," "set," and a "remote procedure invoke." Included is a PC-based simulator allowing serial communications to be tested without a slave embedded device.

While lacking the ultimate flexibility of traditional code-driven interfaces, Amulet's innovative use of HTML makes up the difference with simplicity and rapid development. With a list price of $399, Easy GUI is a unique system that should reduce labor and save time, particularly on embedded projects with basic to moderate screen demands. For more information about Easy GUI from Amulet Technologies: Enter 536

Easy GUI Module kit technical specifications
PCB size: 4.25 x 3.58 inches
LCD: Chip-on-glass, 3.48 x 2.72 inches, black on white, 320 x 240
Dot pitch: 0.24 x 0.24 mm
Dot size: 0.225 x 0.225 mm
Touch screen: 4-wire resistive analog; active area is 80 x 62 mm
Backlight: LED Rimshot, always on, adjustable brightness
Serial port: RS-232, 9-pin DIN, up to 115.2 kbps
Protocol: Half-duplex, Easy GUI client acts as master
Compiler OS: Microsoft Windows 95/NT and up

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