With the rapid development of science and technology, the development of traditional TV, newspaper and magazine media has lagged behind the development of outdoor media. Here we will introduce the system design of dot matrix LED dot matrix display.Composition of LED dot matrix display
Composition of LED dot matrix display: it is a new display device, which is composed of multiple LED's encapsulated together. In order to explain the principle of LED dot matrix display, a display system including hardware and software is designed and manufactured with single chip microcomputer as the control core. The circuit can realize various display forms such as rolling shutter, moving up and moving left of any number of Chinese characters through key control. It can be widely used in public places such as airports, shopping malls and hospitals for text advertising and information release. Moreover, it has the characteristics of small volume, simple circuit structure and easy implementation.
LED dot matrix displaySystem hardware circuitThe hardware circuit of the display controller is mainly composed of three parts: serial communication interface, expansion of external memory, LED dot matrix display driver and interface circuit. Generally speaking, there are many contents to be displayed, so the external data memory must be expanded. Static data memory has the advantages of low cost, low power consumption and fast reading and writing speed. We use two pieces of static ram62256 data memory (64KB in total). Store all the content codes to be displayed in 62256.
System software programSoftware program is the core of the whole control system. After the system main program starts, the system environment is initialized first, including setting serial port, timer, interrupt and port. The whole software design is mainly divided into two parts: display part and communication part.
Communication part: the upper computer software adopts visual basic programming, and VB is used to provide a powerful communication control MSComm, which controls the message format and protocol setting of serial port and serial port communication, and directly uses the serial port of PC to send data. In order to realize the reliable communication between MCU and PC, both sides must have the same data format and baud rate. The use of the software is relatively simple. When using, you can use Microsoft Word to handle the content to be displayed (note that the width of the page setting should be the same as that of the LED dot matrix display), then select the select all command and copy command in the edit menu, and then run the LED display Download Software v1.1. Select the "clipboard" button in the interface, and the content to be downloaded can be displayed in the preview box, After checking, select the baud rate and connect to the serial port, click the "download" button, and you can download the display. Repeat the above operation when you need to modify or display new content. It is very convenient to use.
Display part: use dynamic scanning to realize the control and display functions of Chinese characters, characters, images and data transmission on the display screen. The program divides the data memory into three areas: display buffer, data storage area and receiving buffer. The single chip microcomputer receives the data from the PC through the serial port interrupt, temporarily stores it in the receiving buffer, analyzes and processes it, saves it in the data storage area according to certain rules, and then extracts the data from the data in the memory according to the display mode sequence to display it in the display buffer. The display adopts progressive scanning. The real-time communication part of PC mainly uses the MCU serial port to interrupt the reception of data information and realize the data information transmission with the computer.
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