On a daily basis, I work on firmware for an embedded device that uses the Bridgetek FT800. It’s a nifty chip that takes commands over SPI/I2C and turns them into an image displayed on an LCD. It’s very useful for displaying user interfaces with simple microcontrollers. Bridgetek is actually a spinoff company from FTDI, and this kind of solution seems right up their alley — take something complicated like USB or a display controller, and create a simpler interface for dealing with it, such as UART/SPI/I2C.
One thing that’s usually important about user interfaces is the ability to display text. The FT800 has a very basic capability for handling fonts. It’s not really much more than the ability to deal with sets of 127 sprites that each comprise a “font”. As a developer, if you want to use fonts aside from the (very limited) stock ones that come bundled in the FT800’s ROM, you have to create bitmap images that you upload into the 256 KB of available display RAM.
Several years ago, we had to deal with converting the user interface to display in a bunch of different languages, including Chinese. Most of the new languages we added weren’t a big problem, because we could just create a couple of fonts containing all of the special accented characters we needed and be done with it. Chinese, though, was a bigger challenge. There are so many different characters. Putting every character for every string into the limited display RAM is impossible. My coworker at the time came up with a clever script that automatically rasterized the font glyphs and created groups of different 127-character fonts for each displayed screen in the user interface. Every time you changed screens, the new set of fonts for that screen would be loaded into the display RAM.
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