The pin diagrams of KS0108 based GLCDs is not standardized and it is therefore, important to read the manufacturer’s datasheet for correct wiring of a GLCD module.
An external potentiometer (usually 10 K) is connected between VDD and VEE pins to set the LCD contrast. The AMPIRE 128X64 module does have an internal negative voltage generator circuit which provides a negative voltage at VEE external pin. The total amount of bytes needed for a complete display frame (128×64 pixels) is, therefore, 2 x 64 pixels x 8 bits = 1024 bytes. The next 8 lines can be plotted similarly by switching to page address 1. If you repeat this 64 times, then switch to the second half, and repeat until 128th position is reached, the first 8 display lines will be plotted. Starting from page 0 on the left half (/CS1 = 0) if you transmit one data byte, it will appear on the first column of page 0. This is illustrated in the drawing below. Each half consists of 8 horizontal pages (0-7) which are 8 bits (1 byte) high. The two halves of the display can be individually accessed through the chip select pins (CS1 and CS2) of the two KS0108 drivers. The first KS0108 drives the left half segments (SEG1 to SEG64) and the second one drives the right half segments (SEG65 to SEG128) of the display.
The KS0107 drives the 64 display lines, COM1 – COM64. The internal block diagram of the AMPIRE 128X64 GLCD module is shown below. The KS0108B and KS0107B are a very popular controllers and have made their way into many graphical LCDs. On the other hand, the KS0107B is a 64-channel common driver which generates the timing signal to control the two KS0108B segment drivers.
The KS0108B is a dot matrix LCD segment driver with 64 channel output, and therefore, the GLCD module contains two sets of it to drive 128 segments. It uses KS0108B (or KS0107B) display controller. The graphical LCD used here is AMPIRE 128X64(AG12864EFIQB -H) module, which is a 128×64 pixel monochromatic display. The graphics LCD used here has a pixel size of 128×64 and is based on AG12864EFIQB -H. There are various types of graphics LCD modules available in the market depending on pixel size such as 120×64, 128×128, 240×64,128×64 and 240×128. You write to the graphic RAM to modify its contents and the screen will change accordingly. The GLCD has a graphic RAM where each bit in RAM corresponds to one pixel on screen. ON pixels looks dark while OFF pixels are nearly invisible. These displays are monochrome that means each pixel can either be ON or OFF. That means, their are 64 horizontal lines and each line has 128 pixels. The graphical LCD is made up of a grid of pixels.
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