原 文
题目：LED dot matrix screen design based on MCU
As a popular display device component, LED dot-matrix display board consists of several independent LED (Light Emitting Diode). The LED dot-matrix display board can display the number or sign, and it is usually used to show time, speed, the state of system etc. This paper introduces a kind of simple 16ｘ32 LED display screen design process based on STC89C52 single chip minicomputer . The detail hardware scheme, software flow and C language programmer design and so on is followed. The display part can be cascaded to meet the need. The practice proves the design is low-cost and effective.
First of all know of LED dot matrix, the so-called of LED dot matrix is LED to more array in a way device, can be divided into monochrome, double-color, three kinds of color. According to the arrangement of polarity LED into type of Yin and Yang type two kinds. According to the matrix each line or each column contains the number of different LED, and can be divided into 5 x7, 8 x 8, 16 × 16 type etc. One of the LED's pin regular connection, di折叠炕桌 vided into type of Yin and Yang of type 8 x8 LED array.
Usually the control including glyph LED control (display what characters) and a control (what a display). In the static display mode, each a display of the form the line is independent, respectively, received a eight I/O mouth, the word a line also connected to another I/O mouth. When want to display a character, make corresponding LED light can. Now a lot of billboards would do this. This kind of low cost and easy to implement.
Dynamic display of use of or more extensive, dynamic display is a a turn LED light, in every time only a display in the work (light), but because of the human eye for a visual effect and leds extinguishing rays, will appear more characters "and" showing that the phenomenon. That in every moment, all LED to show the same characters will, to each show the different characters, they must use scanning methods in turn LED light you, that in every moment is a particular display character, in this moment, broken choose control I/O ports output corresponding characters chosen code (font code). And a selected control I/O mouth in the displaying a send in electricity flat in order to ensure the correspo
nding character position shows. So take turns, make each timeshare shows that this position should be display character. For example to show LL0-220, I/O 1 and the I/O 2 take turns into the period of choose code, a selected code and show the state. Choose a code, section choose yards into a delay each 1 ms, because the person's vision for a time a 100 ms, so each show time intervals not more than 20 ms, and keep the delay for a period of time, to temporarily leave cause visual effect, give a person looks in each LED light, and display different content. LED the array of showing the way according to display data coding is the order and a line to display. With high state scanning as an example, if want to show the first line, the first will first line display data (00001000) sent to the LED the array of listed pin, again will "10000000" scanning signals sent to LED the array of line pin, can show the first line, this time the other will not display. Likewise, if you want to show the second line, it will be done to the second display data (00100100) sent to the LED the array of listed pin, again will "01000000" scanning signals sent to LED the array of line pin, can show the second line, this time the other will
51 MCU has four I/O interface, often the control equipment many external, when the four
码图interface is not enough to use, often external many expansion of equipment used in connection with external chip, here, of LED dot matrix display cannot directly to the I/O mouth, you need through the expanded chip and 8051 connection.
Some of the problems about the font, first have a take font software, it can be one of the Chinese characters and image is decomposed into their respective font, font is the LED screen when displayed by the need to invoke dictionaries, through the modification to revise the word to the content of the show. Take font software has a lot of. You can also download on the net. The software and many functions, transverse take font can undertake right movement, vertical mold can take to move up or down, and so on.
How to control the font and rolling rolling speed, font is the continuous rolling screen display, then first have to know how to display a screen: a screen (full screen) display is displayed by line, quickly. Make the person produces the visual error, feel the entire screen is in the light. In the show by line, show the one line to delay for a while. Here the delay time to determine the t1 shows the time of each screen, that is the dynamic display
珍珠岩保温管壳of speed). 16 × 16 bitmap screen, for example, the first to perform on display, delay, a total of 16 line shows. Then the 16 line that repeated several times, to better see the screen display. (here several times of the number of times the n1 also decided to display the speed). And change the delay time or the number of repeat t1 that can change the rolling n1 speed, when increase the two value, the scrolling speed will slow down, reducing the when two value, the scrolling speed can be accelerated. The font displayed by the principle for screen, a font of by how much screen, is how many of the display screen. Since 2000, the LED lawn lamp, traffic light, flashlight, floor lamp, landscape lamp began to enter the market, through the development in recent years, the scale more growth. From the application for the development of the product, the first thing is to put the new application developed. April 2008 in Frankfurt, Germany, in the lighting show on 80 companies using Luxe on function device developed application products. However, thinking about what the product development, must play LED itself from aspects of advantages, such as from its long life, moistureproof, bear the vibration characteristics, c
an develop indoor lighting, museum, safety becon light export symbol lamp, flashlight; From focusing the gender is good, characteristics, can develop thin form lamps, small desk lamp, advertising light box, stage lights and coal mine lamp; Low voltage, quick drive from the characteristic, can develop a flashlight, maintenance lamp, buried lights, lawn lamp light and water.
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