With the rapid development of technology, the development of traditional TV, newspaper and magazine media has lagged behind the development of outdoor media. Here we will introduce you to the system design of dot matrix LED dot matrix display.
LED dot matrix display composition
The composition of the LED dot matrix display: consisting of a plurality of LED light emitting diodes packaged together, is an emerging display device. In order to explain the principle of LED dot matrix display, a display system consisting of hardware and software is designed and fabricated with the single chip as the control core. The circuit can realize various display forms such as rolling shutter, upshifting and left shifting of any number of Chinese characters through button control, and can be widely used in public places such as airports, shopping malls, hospitals, etc. for text advertisement promotion and information release. Moreover, it has the characteristics of small size, simple circuit structure and easy implementation.
LED dot matrix display
System hardware circuit
The hardware circuit part of the display controller is mainly composed of three parts: serial communication interface, external memory expansion and LED dot matrix display driver and interface circuit. Generally speaking, there is a lot of content to be displayed, so it is necessary to expand the external data storage. Static data memory is low cost, low power consumption, fast read and write speed, we use two static RAM62256 data memory (64KB total). Store all the content code to be displayed in 62256.
System software program
Software programs are a core part of the overall control system. After the system main program starts, it first initializes the system environment, including setting serial port, timer, interrupt and port. The entire software design is divided into two major parts: the display part and the communication part.
Communication part: The upper computer software adopts Visual Basic programming, and uses VB to provide powerful communication control MSCOMM. The control serial port and serial port communication message format and protocol setting directly use the serial port of PC to send data. In order to achieve reliable communication between the microcontroller and the PC, it is necessary to ensure that both parties have the same data format and baud rate. The use of this software is relatively simple. When using, you can use Microsoft Word to process the content you want to display (note that the width of the page setting should be the same as the width of the LED dot matrix display), then select the Select All command and Copy command in the Edit menu, then run the LED display to download the software. In the V1.1. interface, select the “Clipboard†button. The content that needs 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, you can download the display. Repeat the above steps when you need to modify or want to display new content. It is very convenient to use.
Display part: Using the dynamic scanning method to display Chinese characters, characters, images and data transmission control and display functions on the display screen. The data memory is divided into three areas in the program: display buffer, data storage area and receive buffer. The MCU receives the data transmitted from the PC through the serial port, temporarily stores it in the receive buffer analysis process, saves it in the data storage area according to certain rules, and then extracts data from the data in the memory to the display buffer according to the display mode sequence. . Shows the method of using progressive scanning. The real-time communication part of the PC mainly uses the serial port of the single-chip microcomputer to interrupt receiving data information, and realizes the data information transmission with the computer.
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