Using LEDs, LCDs and GLCDs in Microcontroller Projects

7.1 The 128 × 64 Pixel GLCD

These GLCDs have dimensions 7.8 × 7.0 cm and a thickness of 1.0 cm. The viewing area is 6.2 × 4.4 cm. The display consists of 128 × 64 pixels, organised as 128 pixels in the horizontal direction and 64 pixels in the vertical direction. The display operates with +5 V supply, consumes typically 8 mA current, and comes with a built-in KS0108 type display controller. A backlight LED is provided for visibility in low ambient light conditions. This LED consumes about 360 mA when operated.

The block diagram of the GLCD is shown in Figure 7.1. Basically, two controllers are used internally: one for segments 1 to 64, and the other for segments 65 to 128.

Figure 7.1 Block diagram of the GLCD with KS0108 controller

The display is connected to the external world through a 20-pin SIL (Single-In-Line) type connector. Table 7.1 gives the pin numbers and corresponding pin names.

Table 7.1 128 × 64 pixel GLCD pin configuration.

Pin No	Pin Name	Function
1	\CSAor CS1	Chip select for controller 1
2	\CSB or CS2	Chip select for controller 2
3	VSS	Ground
4	VDD	+5 V
5	V0	Contrast adjustment
6	D/I	Register select
7	R/W	Read-write
8	E	Enable
9	DB0	Data bus bit 0
10	DB1	Data bus bit 1
11	DB2	Data bus bit 2
12	DB3	Data bus bit 3
13	DB4	Data bus bit 4
14	DB5	Data bus bit 5
15	DB6	Data bus bit 6
16	DB7	Data bus bit 7
17	RST	Reset
18	VEE