TFT - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 227

at 750 lbs (340 kg). If you wanted a big screen, you made sure you had friends
available to help you install it.
The arrival of LCD screens changed home theater technology at a speed
that has rarely been seen. LCD seems to have many advantages over CRT; it
is relatively cheap, lightweight, robust, and easier to recycle. Screens could
suddenly become bigger, but ironically, they could also become smaller. Large
CRT screens were impractical for their size, but similarly, who could honestly
imagine a mobile telephone with a CRT screen? Old mobile computers did have
CRT screens though. They weren't the clamshell shape that you can see today;
rather, they were like large bricks. The keyboard came off the top, and on one
side was a CRT screen with l oppy drives on the other. LCD screens not only
made mobile telephones possible, but also changed the way mobile computers
are used.
Te chno lo gies
Many screen technologies have been introduced since the introduction of LCD
displays, each generation addressing problems and inconveniences of the pre-
vious technology.
One of the i rst changes was the introduction of passive matrix addressing.
This technology allowed a single pixel to be changed by addressing its x -and
y -coordinates, and pixels retained their state until ordered to change. This
technology was reliable but offered slow refresh rates and became impractical
as the screen resolution increased.
Dual Scan, known as DSTN (short for dual-scan supertwist nematic), gave
faster screen refresh rates but at the cost of sharpness and brightness. DSTN
screens were uncomfortable for watching i lms; there was visible noise and
smears on these screens. I can remember taking a long-haul l ight where a
new multimedia system was installed on every seat but using DSTN screens.
(Previously, l ying was like going to a cinema, one large screen for a single
cabin.) The lack of screen comfort actually made me stop watching a i lm and
prefer reading in-l ight magazines.
TFT, short for Thin Film Transistor, is another technology for displays.
Originally, it was much more expensive compared to DSTN panels, but pro-
duction costs were reduced as demand increased. TFT allows for crystal clear
text and graphics, with superb colors. TFT panels are used in almost all mobile
devices and nonportable equipment such as televisions and computer monitors.
The ST7735 is an integrated circuit that can drive small-sized TFT displays
(128 x 160 pixels in size). An Arduino or other device can communicate with the
ST7735 which will talk to the screen. Because the driver has on-board memory