Liquid Crystal Display (LCD) has the advantages of power saving, small size and strong anti-interference ability, and is divided into segment type, character type and graphics type.

(1) Segment type. Character display is composed of strips, mainly used for digital display, and can also be used to display letters or certain characters, widely used in water meters, electricity meters, calculators, and digital instruments.

(2) Character type. Specially used to display letters, numbers, symbols, etc. A character consists of a 5x7 or 5x10 graphics, which has been widely used in microcontroller systems.

(3) Graphic type. Widely used in graphics displays, such as Lap top, color TVs and game consoles. It is a matrix of lattice points with multiple rows and columns arranged on a flat panel. The size and number of points determine the clarity of the display.

Introduction to COB1602 Liquid Crystal Display Module

Character LCD is often used in single-chip application systems, also known as COB (Chip On Board). Because the LCD display panel is relatively fragile, the manufacturer has connected the LCD controller, driver, RAM, ROM and the LCD panel together with a PCB, called the LCD Module (LCM), and the user only needs to buy ready-made liquid crystals. Just show the module. The single-chip microcomputer can display the required content as long as it writes the corresponding commands and data to the COB display module. COB 1602 is the most common character type LCD module.

Character LCD 1602 features and pins Character COB modules commonly include 16 characters x 1 row, 16 characters x 2 rows, 20 characters x 2 rows, 20 characters x 4 rows, etc. The models are commonly used 16*02, 16* 04, 20*02, 20*04, you can add the abbreviation of the brand name in front of the model, 16 means that each line of the LCD can display 16 characters, and 02 means that it can display 2 lines. LCD1602 has a character library ROM (CGROM) inside which can display 192 characters (5x7). The figure shows some characters.

It can be seen from the character library that the codes of the numbers and letters displayed are exactly the codes in the ASCII (American-Standard Code for Information Interchange) table. When the single-chip microcomputer controls COB1602 to display characters, it only needs to write the ASCII code of the characters to be displayed into the internal display data RAM (DDRAM), and the internal control circuit can display the characters on the COB. For example, to display the character "A" on the COB, the microcontroller only needs to write the ASCII code "41H" of the character "A" into DDRAM, and the control circuit will write the graphic of the character "A" in the corresponding character library ROM (CGROM) The data is found and automatically displayed on the COB.