Using LEDs, LCDs and GLCDs in Microcontroller Projects

6.1 HD44780 Controller

HD44780 is perhaps the most popular LCD controller module used in microcontroller projects and it is currently the industry standard LCD module. This module is monochrome and comes in different shapes and sizes. Depending upon the requirements, displays with 8, 16, 20, 24, 32 and 40 characters are available. The row size can be selected as 1, 2 or 4. Display types are identified by specifying the number of rows and number of characters per row. For example, a 1 × 16 display (see Figure 6.1) has one row with 16 characters, and a 4 × 16 display has 4 rows and 16 characters on each row (see Figure 6.2).

Figure 6.1 1 × 16 LCD display

Figure 6.2 4 × 16 LCD display

The LCD normally has 14 pins for connection to the outside world. The pins are usually organised in a single row and numbered 1 to 14, as shown in Figure 6.3. Those with backlights have two additional pins. Table 6.1 shows the pin configuration. The device is normally operated from a voltage +3.3 to +5 V.

Figure 6.3 LCD pins

Table 6.1 LCD pin configuration.

Pin no	Name	Function
1	Vss	Ground
2	Vdd	+V supply
3	Vee	Contrast adjustment
4	RS	Register select
5	R/W	Read/write
6	E	Enable (clock) ...