LCD and CTP Interface Introduction-MCU /Parallel Interface

There are several ways of connecting MCU (Microcontroller Unit) or MPU (Microprocesser Unit) or CPU (Central Processing Unit) with LCD, MCU/Parallel interface is one of them.

Fig. 1 Connection Between MCU to LCD

Basic knowledge introduction (1):LCD Driving Waveform

LCD can’t be driven with DC (Direct Current), it has to be driven with AC (Alternative Current) and the overall current has to be ZERO. Otherwise, the Liquid Crystal Material will be damaged sooner or later.

Fig. 2 LCD Driving Waveform

Basic knowledge introduction (2):LCD Controller vs Driver

There are two types of Driver IC’s, Common Drivers and Segment Drivers. Common Drivers output signals to create the rows or numbers of lines. The Segment Drivers output the necessary signals to create the characters or columns.

The Controller IC receives data written in ASCII or JIS code from the MPU and stores this data in RAM. This data is then converted into serial character patterns and transferred to the LCD driver IC.

Drive/Controller IC is probably the most commonly found in a graphics module. This IC receives data from the MPU and stores it in RAM. Also, it accepts commands directly from the MPU for both the common and segment drivers.

MCU /Parallel Interface

MCU interface include two types, 6800 and 8080. 8080 is the much more popular than 6800. Generally, MCU interface consist of 4/8/9/16bits data (like DB0, DB1, , , DB7; Note: 8bits is the most popular bits width), CS (chip select), RS (data register or instruction register select), RD (read enable), WR (write enable).

PROs: Simple

CONs: Need RAM, Speed is limited.

Used in Mono character, graphic, small TFT (smaller than 3.5”)