Character LCD tutorial
Mini Character LCD Tutorial
As a simple character LCD tutorial we will discuss things relating to character (alphanumeric) LCD modules such as the character table; chip on board, font size, display configurations, features, advantages and disadvantages.
Character LCD displays are used in applications such as credit card machines, vending machines, and test and measurement equipment. This module has the ability to display letters, numbers and punctuation. A character is any letter–capital and non-capital–any number and a punctuation mark (i.e. a period, comma, back slash, etc.).
Character LCD Displays Make Use of a Character Table
The character LCD display, sometimes referred to as an alphanumeric display, is equipped with a character table that has pre-loaded letters, numbers, and punctuation. The table allows the designer to call out the requested character by addressing the number of that character. In other words, the letter ‘M’ may be the number 24 and the “!” could be number 147. This eliminates the need to create each charter from scratch and reduces the amount of time necessary to program the LCD module. In the font table below the letter ‘P’ would be displayed when the designer calls for the following character number sequence:
D0=0, D1=0, D2=0, D3=0, D4 =0, D5=0, D6=1, D7=1, D8=0
The letter Do, D1, and so on above means data bit 0, data bit 1 etc. Most character displays use eight data bits.
The character table above is built into the micro controller, also called a controller driver, of the LCD and can display 255 separate characters. Of course there are different languages, so you can choose a character table that displays English, French, German and many other languages.
Chip on Board Character LCD Display
The font table, also called a character set, is programed into the on-board controller driver that is attached to the back of the LCD. The black dots below are epoxied to the PCB (printed circuit board) in order to protect the controller driver chip from moisture and dirt. This type of display is called COB or Chip on Board. This type of module handles vibration very well.
Character LCD Display Font Size:
The standard font size of a character LCD display is 5 dots horizontally and 8 dots vertically. The character is created by turning on and off the correct dots. Below the small letter ‘b’ is displayed by turning on specific dots.
The 5 x 8 font size works well for English and other alphabet-based languages. This system does not support pictorial languages such as Chinese, Japanese, and Korean. A larger font size with a dot count of 16 dots by 16 dots is required.
Character LCD Display Configurations
Character LCD Displays are built in standard configurations such as 16×2, 8×1, 20×2 and 40×4. The identification of these displays is broken down into the number of characters in each row and then the number of rows. An example of this is a 16×2. That means there are 16 characters in each row. There are two rows of these characters. Below is a complete list of all standard character LCD display configurations.
- 8×1, 8×2
- 16×1, 16×2, 16×4
- 20×1, 20×2, 20×4
- 40×1, 40×2, 40×4
Character LCD Display Features:
- The character table is built into the controller/driver chip and allows you to quickly program the display.
- Controller/driver chips come with the option of different languages. This allows the original equipment manufacturer (OEM) to build one product and offer it in different locations/languages.
- It’s available in standard configurations across the industry, in other words the exact display is available from multiple sources.
Character LCD Display Advantages:
- Built in controller/driver chips allow easy interface to the customer’s MPU (microprocessor unit).
- Follows industry standards that allow a change in suppliers.
- Lower MOQ’s (minimum order quantities) of 100.
Character LCD Display Disadvantages:
- Cannot display graphics that are available in Graphic LCD Displays.
- Requires more power than a static display.
In conclusion, we hope this mini character LCD tuturial was helpful in explaining some basic features of the alphanumeric LCD. For more information regarding these displays, please see our standard Character LCD page which provides even more detailed information and where you can purchase our standard configurations.