Chapter 7

Graphics LCD Displays (GLCD)

Graphics LCD displays (GLCDs) are commonly used in many scientific applications, where we may want to display graphical data, such as a bar-chart or x-y line graph, for example a graph showing the change of temperature over time, and so on. GLCDs are also used in many consumer applications, such as mobile phones, MP3 players, GPS systems, games, educational toys, and so on. Another important application area of GLCDs is in industrial automation and control, where various plant characteristics can easily be monitored or changed.

Most GLCD applications nowadays make use of touch-screen facilities. As we shall see later, a touch screen is basically a transparent layer with touch sensitive cells, placed on top of a standard GLCD. When the user touches the screen, the screen co-ordinates of the touched point are sent to the processor. For example, nearly all mobile phone manufacturers offer touch-screen phones, where users can easily navigate between different screens and make choices by simply touching on the displayed items, thus avoiding the use of buttons for screen navigation.

There are several GLCD screens and GLCD controllers in use currently. For small applications, the 128 × 64 pixel monochrome GLCD with the KS0108 controller is one of the most commonly used displays. For larger display requirements and more complex projects, we can select the 240 × 128 pixel monochrome GLCD screen with the T6963 (or RA6963) controller. For colour GLCD based applications, TFT type displays seem to be the best choice currently.

In this chapter we shall be looking at how the standard 128 × 64 GLCD can be interfaced and used in microcontroller based projects. In addition, the principles and use of the touch-screen displays will be described in this chapter. The use of 240 × 128 pixel GLCDs and TFT based colour GLCDs will be described in later chapters, when we develop display based projects.