With the advancement and wide application of digital science, the concept of media integration has become more and more perfect. Outdoor media has also become the new favorite of China's advertising industry in the 21st century, and its development potential is much higher than that of traditional TV, newspaper and magazine media. This article introduces the system design of dot matrix LED dot matrix display.
1. Composition of LED dot matrix display: It is composed of multiple LED light-emitting diodes packaged together and is an emerging display device. In order to explain the principle of LED dot matrix display, a single-chip microcomputer is used as the control core, and a display system including hardware and software is designed and manufactured. This circuit can realize various display forms such as rolling, 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, hospitals, etc. for text advertising and information release. And it has the characteristics of small size, simple hardware circuit structure and easy implementation.
2. Introduction of system hardware circuit: The hardware circuit part of the display controller is mainly composed of three parts: serial communication interface, expansion of external memory and LED dot matrix display driver and interface circuit. Generally speaking, there are more contents to be displayed, so the external data storage must be expanded. Static data storage has low cost, low power consumption, and fast read and write speed. We use two static RAMs 62256 data storage (64KB in total). Store all the content codes to be displayed in 62256.
3. Introduction of system software programs: Software programs are the core part of the entire control system. After the main program of the system starts, it first initializes the system environment, including setting serial ports, timers, interrupts and ports. The entire software design is mainly divided into two parts: the display part and the communication part.
1. Display part: Use dynamic scanning to realize the transmission and control functions of displaying Chinese characters, characters, images and data 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 from the PC through the serial port interruption, temporarily stores it in the receiving buffer for analysis and processing, and saves it in the data storage area according to certain rules, and then extracts the data from the data in the memory to the display buffer according to the display mode sequence . The display uses progressive scanning. The real-time communication part of the PC is mainly to use the serial port of the single-chip microcomputer to interrupt the reception of data information and realize the transmission of data information with the computer.
2. Communication part: The upper computer software is programmed with Visual Basic, and VB is used to provide a powerful communication control MSCOMM. The control serial port and serial port communication message format and protocol settings directly use the serial port of the PC to send data. In order to achieve reliable communication between the microcontroller and the PC, it must be ensured that both parties have the same data format and baud rate. The use of this software is relatively simple. When using it, you can first use Microsoft Word to process the content that needs to be displayed (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, and then run the LED display to download the software V1.1. Select the "Clipboard" button in the interface, 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, you can download the display. If you need to modify or display new content, repeat the above operation to complete. It is very convenient to use.
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Antenk MICRO USB :Micro USB is a miniaturized version of the Universal Serial Bus (USB) interface developed for connecting compact and mobile devices such as smartphones, MP3 players, GPS devices, photo printers and digital cameras.
Micro USB connectors exist or have existed in three forms: micro A, micro B and micro USB 3. USB 3 micro is much like micro B, but with an additional pin group on the side for twice the wires, enabling USB 3's greater speed. Like standard USB, the micro versions are plug-and-play and hot-swappable.
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