The Development Of A Serial-Type LCD Based On Embedded System

With the rapid development of the display technology and the embedded technology, the display technology based on the embedded system has been widely used in many fields. As one way of the realization of the human-computer communication visualization, the display system is put forward higher requirements on image quality, display content and other function in the fields of industrial control. In order to change the disadvantages of low image quality, slow transmission speed, single display contents of the present serial-type liquid crystal display (LCD), the paper designed a serial-type LCD based on embedded system which has the following advantages: can display the graphics and curves, show clear pictures, and support the RS-232 and USB high speed communication protocol. It will play an important part in the industrial control fields which need the serial-type clear display devices.The serial-type LCD system is mainly consists of the following five parts: central processing unit, display unit, power unit, communication unit and miscellaneous function unit. The central processing unit uses the FREESCALE Company i.mx233 micro-controller which is based on ARM9 architectures. Meanwhile, take DDR1 SDRAM and NAND Flash with 64MB memory capacity as external memory which is used to save the data of startup code and system information and so on. The display unit uses the TFT-LCD (Thin Film Transistor-LCD) which has the advantages of small size (3.5inch) and high resolution (320*240). The LCD unit is directly controlled by the internal LCD controller of the i.mx233. The power unit is designed by the low-voltage (Li-Ion Battery4.2V) which can realize the low power consumption (1.2W) of the device. The communication unit is configured to the simple RS-232 interface protocol or the USB virtual serial port. The information which transmitted by the serial port can be clearly displayed by the LCD. The miscellaneous function unit includes the WiFi wireless communication, TF card and audio part which can reduce the secondary development difficulty. It increases the reliability and portability of the system through the design of the two layers and single layout PCB board, wiring and volume problems considered.During the realization of the system, with the works of the project, the system starts from the NAND Flash which is guided by the USB port under the environment of the virtual machine. In the test part, the system can not only meet the electrical performance requirements, but also can realize the higher speed data transmission through the serial port and USB which is showed in the experimental waveform. At the same time, the system can realize the data and image from the serial port displayed clearly on the LCD which has higher application value and research significance.