Issue 132 July 2001
Liquid Crystal Delight

Start • Working Glass Hero •Quarter Horse •Software To Boot •Widge Warrior •Highway Star •Beta Site •Take It Easy •Sources & PDF

QUARTER HORSE
What the world really needs is a fully integrated, easy-to-use solution for middle-of-the-road LCD display applications. That’s exactly what Amulet Technologies aims to deliver with its aptly-named Easy GUI package of chips, boards, modules, and software tools (see Photo 1). Configurable to support a variety of panels and resolutions, Easy GUI targets the so-called 1/4 VGA (320 × 240) sweet spot, fitting squarely between the resolution offered by the old war horses (e.g., 256 × 64 for the venerable Hitachi LM213B) and the full-blown megapixels of an embedded PC.

Easy GUI technology starts with a chip of Amulet’s own design (see Figure 1). Packaged in an 80-pin PQFP, the AGB64LV01 integrates an 8-bit microcontroller with LCD interface logic including a line buffer and programmable timing generator. External interfaces include an 8-bit data bus for an SRAM, 8-channel SPI port for serial EEPROM and other peripherals, UART for host connection, and the LCD panel interface.

The latter consists of a pixel data bus and a half dozen video-like timing and control signals. Various characteristics are programmable, such as pixel bus width (1, 2, 4, or 8 bits) and pixel and frame clock polarity, to accommodate a variety of manufacturers’ panels. At this point, Amulet supports only monochrome panels, but it’s not hard to imagine a color follow-on.

Figure 2 is the schematic for a typical board design, much like the one that comes with the starter kit (see Photo 2). The Amulet Technologies chip is hooked to a serial EEPROM that stores the user-defined screens and a byte-wide SRAM used for both the display frame buffer and working storage. An RS-232 level shifter and the usual 9-pin connector complete UART connection to the host.

Figure 1—The Amulet Easy GUI chip ($17.50 in 10k units) combines a micro with custom graphics extensions, a 256-byte line buffer, and an LCD interface with programmable timing to accommodate a variety of displays.

Also shown on the schematic is a Burr-Brown (now part of Texas Instruments) ADS7486 touchscreen controller. This little puppy handles all the details of connecting a resistive touchsceen overlay for “Look ma, no mouse” embedded apps. That’s a nice touch.