LCD Display Controller Driver | Introduction

Character and Graphic displays are supplied with an on-board LCD display Controller Driver. This also can be referred to as an IC (integrated circuit) driver. There are different manufactures of LCD display Controller Drivers such as Sitronix, Epson and Sunplus.

The LCD display Controller Driver has three main functions

1. RAM

  • This is the memory built into the controller driver that helps to drive the LCD.

2. Character Generator

  • This is a library that converts the customer’s data to letters, numbers and Punctuation marks.
  • The character generator is different for each language.
  • The SPLC7066U controller driver can supply up to 240 character fonts.

3. Liquid Crystal Driver

  • This drives each segment (dot)

The Sitronix C/D ST7066U has the ability to drive 640 segments. If you need to drive more than 640 segments, then you will need to add on an additional ‘segment driver’. The Sitronix version of the segment driver is the ST7063C and ST7065.

What is a segment?

A 16×1 character display can display one row of 16 characters. Each one of these ‘16’ characters is made up of ‘dots’ or segments. Each of these characters can be 5×8 (5 dots along the horizontal and 8 dots up and down). There are also characters that have 5×11 dots and 10×10 dots.

Above is a drawing of a 16×1 Character display that has a 5×8 character size.

Each of the 5×8 character has 40 dots or segments (5 x 8 =40). Therefore a 16×1 character display has 16 characters with each character having 40 dots. This means that the 16×1 display has (16 [characters] x 40 [dots]) = 640 dots or segments.

One LCD display controller driver can handle all the functions of 640 segments. This is equivalent to a 16×1 character display, an 8×2 LCD or 8×1 Character display.

If you need a larger display such as a 16×2 or 20×2 you would add a segment driver such as the ST7063C. There is no need for another controller. Each display only needs one controller but can contain many additional segment drivers.

The segment driver does not have the ability to supply RAM and the character generator. The sole purpose of the segment driver is to drive the segments.

Below is a break down of how many LCD display controller drivers and segment drivers are needed for a character display. This is for monochrome LCD modules.

A 16×1 requires one ST7066.
A 16×2 requires one ST7066 and one ST7065 (segment driver)
A 20×2 requires one ST7066 and one ST7063 (segment driver)
A 16×4 requires one ST7066 and two ST7063 and one ST7065
A 20×4 requires one ST7066 and two ST7063’s.
A 40×2 requires one ST7066 and two ST7063’s.
A 40×4 requires one ST7066 and four ST7063’s.

The Focus Display standard offering of Alphanumeric and Numeric LCD Displays includes:
8 x 1 LCD Display, 8 x 2 LCD Display, 16 x 1 LCD Display, 16 x 2 LCD Display, 16 x 4 LCD Display, 20 x 2 LCD Display, 20 x 4 LCD Display, 24 x 2 LCD Display, 40 x 1 LCD Display, 40 x 2 LCD Display, 40 x 4 LCD Display,

Static displays, also called segment LCD or glass liquid crystal displays do not come with an on-board LCD display Controller Driver. The customer needs to supply the segment driver on their product.

The Focus LCDs standard offering of LCD modules includes:
LCD segment display, 7(seven) segment LCD display, 14(fourteen) segment LCD display, and 16 (sixteen) segment LCD displays.