Home >color tft lcd module > Color LED large screen display asynchronous design
Color LED large screen display asynchronous design
2011-12-14 by seoer1

Development of information technology to promote the flat panel display (FPD) technology continues to progress, China LCD module (liquid crystal), PDP (plasma) and LED (light emitting diode) displays and other display screen in the field of new technologies are widely used. Which, LCD (liquid crystal) technology to become mainstream, many of its products, the market mechanism is more mature. Although color TFT LCD module technology has achieved great success, but people still did not stop to explore and research new technologies, LED display technology is the emergence of new technologies in recent years, LED technology with its unique high brightness, low power consumption, long service life been more and more attention. LED-based technology has been widely used for large-screen display squares, airports, stadiums and stations and other public places, on the big screen to display text, animation, images and video and other multimedia information. LED large screen display information control system, does not require a computer for data processing, is directly read the stored information in the display buffer to display, when the need to update the information, the display of the data acquisition module to the display module send new data. In this paper, high-speed data storage and processing of technical methods, asynchronous design of a color LED large screen display control system.

1 System Design

1.1 The overall framework of the system

This design of LED large screen display control system framework shown in Figure 1

It can be seen from the figure, the system includes the following four components:

1) PC user control platform section, mainly used for image data compression and display information on the changes;

2) ARM-based communication interface part of the screen, used to implement communication with the PC, PC to receive part of the image data and control signals;

3) Based on CPLD and ARM part of the big-screen main controller to achieve the image grayscale modulation and reconstruction;

4) large-screen display driver circuit portion, for large-screen LED lamp to provide constant current drive.

Figure 2 shows the data flow diagram for the system.

1.2 Hardware Design

There are two main host processor for display control system, one is the ARM, the other is produced by ATMEL 89055. Because ARM is not only fast speed, but also a variety of real-time digital signal processing, it is suitable for LED large screen control system during operation of the host processor needs to move large amounts of data characteristics, but also for the design of software programming late leave plenty of time and space. Therefore, we selected the main ARM processor-based systems.

1.2.1 Communication Module

LED large screen in the asynchronous control system, you can display different information offline. Therefore, the realization of large-screen display, real-time update and adjustment of the LED large-screen control system design must be an important part. LED display for communication with the host computer to design and research, its purpose is to fast, reliable access to the adjusted display. Therefore, this design system provides three kinds of communication, namely, Ethernet communications, serial communications and radio frequency communications. These three means of communication not only enhance the communication performance, and easy for users to use.

1.2.2 Display Control Module Design

LED large screen display control circuit control system is an important part in the display control logic circuit generates control signals to read and write access to the display buffer and the address of the data, display data read out by the display driver to the LED display display. Display control module of the read / write address generator, counter, read / write address selector, read / write selector, read / write signal generator, shift latch and synchronization controller and other components.

LED large screen to display a complete graphical images, CPLD and ARM must be concerted work done in the graphics display memory read image data, extract, image display production, and generation of display grayscale modulation various parts of the drive logic functions. Display control module, the hardware structure shown in Figure 3.

In the control circuit, the data bus connected between the CPLD and ARM, S3C44B0X gating by CPLD chip 2 in the data buffer, so the ARM output data of the base address of 0x40000000. FLASH ARM first copy the image data stored to the SDRAM, after the relevant treatment, call the program a different dynamic display image data to the SDRAM write cycle CPLD buffer, CPLD generates the appropriate timing of conversion, serial output to LED driver circuit.

2 LED large-screen control system software design and implementation

Taking into account the system efficiency of the hardware drivers and software development cycle, the system uses the C language as a software development tool.

Design applications to achieve the connectivity with the display hardware, a system to the underlying hardware and driver communication, second, to provide users with the control interface and can receive user input various instructions. To this end, the use of Visual C + + as a system application development tools. Communication applications using MSComm (Microsoft Communications Control) control to write, MSComm is simplified to provide users with Microsoft Window, the serial communication programming ActiveX controls. MSComm control external devices via the serial port for data transmission and reception, can provide applications with serial communication capabilities. Serial port using MSComm control programming is very fast and convenient. MSComm control is based on event-driven, in general, in the event must be notified. In actual programming, you can add OnComm event handler handling code you write, OnComm event handler also checks and processes in the communication error occurs during the operation. The biggest advantage is OnComm control program response time is very short, high reliability. Each MSComm control corresponds to a serial port. If the application needs to access multiple serial ports, it is necessary to use more MSComm control. MSComm control behavior is determined by its various properties. In VC + + can be set through a series of member functions of these properties to control the serial port data format, baud rate and other features. In addition, the VC + +, MSComm control as classes derived CWND appears in the system initialization to create the window, and use the member function to set its properties, it and the next crew to use the same communication format, otherwise it is can not establish proper serial communication.

3 Conclusion

Currently, the existing LED large screen control system, there are many 8-bit or 16-bit microcontroller as the main system processor, the system has lower speed, less storage space, a single means of communication and data transfer speed and slow shortcoming. To address the above problems, this paper designs a new LED large screen control system, as the main system using ARM processors, programmable logic device design with the system drive circuit, a curtain of induction led large-screen color images, text and video display.

  keywords:color tft lcd module