800×600 graphics from an 8-bit MCU

An 8-bit microcontroller can now operate a 800×600 colour LCD graphics screen, and video is possible, thanks to a higher resolution faster version of the Eve graphics processor from Glasgow chip firm FTDI.

Hardware acceleration means jpeg image decode 500-1,000x faster than on the original 512×512 Eve, and a single ‘rotate’ instruction automates portrait-landscape switching for the host processor.

Eve chips directly connect to a microcontroller at one end, and to a 18-bit or 24-bit colour LCD at the other end.

Breaking with graphics tradition, there is no frame buffer RAM or need for a high-end microcontroller.

Instead, a simple host microcontroller loads a list of primitive objects (‘draw a line’ or ‘draw a circle’, for example) into Eve’s execution list and the chip does the rest, rendering line-by-line on-the-fly at 1/16th pixel resolution, rather than pixel-by-pixel.

There are also what FTDI engineering support manager Gordon Lunn describes as widgets – for example, a single widget object draws a clock at a specified location, rather than the host separately defining 13 circles and three lines. Primitives and widgets are all four bytes.

Images, overlays, fonts and templates are also treated as objects, as are beep and chirp instructions to the sound output.

For interaction, there is a touch screen interface with resistive or five-point capacitive options.

Diaplays can be sophisticated – the earlier FT800 Eve chip is used in Gameduino, a graphics add-on for Arduino that enables it to play vintage video games.

For 800×600 variants, object list RAM is up to 1Mbyte from 256kbyte, data transfer is speeded by a quad-SPI option, pixel are drawn at 16/clock rather than four, and algorithm enhancements mean smooth video playback.

Multiple palettes are supported, covering 16bit and 32bit colours with transparency. Extra-large ROM fonts have been added so that there is greater scope when it comes to using different text options.

Firmware memory operations – such as copy, fill and CRC – are two to four times faster through improvements to inner processing loops, while the display snapshot command is hundreds of times faster.

As well as sound out, there is an analogue input pin for interfacing to external audio, a temperature sensor, or light sensor.

Part options are: FT810Q to FT813Q, covering 18bit (7x7mm 48pin VQFN) or 24bit (56pin) RGB interfacing, and the choice of resistive or capacitive touch.

Embedded World Exhibition takes place in Nuremberg, Germany 24-26 February.

steve bush

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via Yuichun