Outdoor LED display hardware circuit and software design of switch power supply

LED display with a power supply switch power belongs to the power grid, rated voltage not exceeding 600 v output type ac - single road External power supply, dc outdoor LED switching power supply is more strict than indoor mainly environmental impact is bigger. So the outdoor LED display of the power switch is the key of the research is more representative. The study of the LED display used for 8 x 8 dot matrix display screen, focuses on the dynamic processing method, due to the limitation of the display screen, in the study design can only display English and Numbers. A basic LED screen from line 8 x 8 point, a total of 64 LED display screen has a total of Yin and Yang two connection ways. Design ideas of composed of 8 x 8 dot matrix LED display, general data connected the 8-bit parallel data port of the microprocessor, and the gate terminal can make them one by one ( Gate) , the choice need to light a column, realize the dynamic display effect by way of time-sharing multiplexing. Gate way generally has two kinds: independent gate and decoding strobe. If the screen is small, the processor has enough I/O ports is available, you can each I/O port connected to a gate, as shown in figure 1. If the screen is bigger, or the processor's I/O port is not very rich, you can through the decoding way to gate, as shown in figure 2. For example when 8 of 8 x 8 dot matrix LED an 8 x 128 lattice LED screen, direct gate way to 64 I/O port, and decoding strobe way need only six I/O port. Hardware circuit in the LED display system, using an 8 x 8 display, so the gate eight I/O port, a gate way to adopt independent gate way. Through software Atmega16 I/O port to provide strobe signal. Atmega16 does not need additional its drive circuit, software Atmega16 has the ability of direct drive. Display system circuit diagram is shown in figure 2. Software design 8 x 8 dot matrix LED display of characters need to convert the actual display by means of modulus data, this process can be done by PctoLCD2002 software, as shown in figure 4, PctoLCD2002 is a LCD matrix generation software, also suitable for font generated for lattice LED screen. Choice of the specifications of the generated by English characters here is 8 x 8 dot matrix, at the same time set the modulus mode for the cathode ( Light up the bits to 1) , per column type and consequent ( High in the former) 。 Conclusion through the research of LED display screen display system, focus on the display of the LED screen dynamic methods, respectively used two timer to control the brightness of the display screen and display dynamic shift speed of the characters. LED screen display system, schematic diagram design under DXP2004, according to the characters can be modulus by PctoLCD2002 software in the system design, according to the actual type of LED screen and circuit connection Settings, choose the suitable way of cathode modulus. Using LED switching power supply, applicable laws and regulations and standard requirements, to assess and review the new product development design, safety science and effectively monitor the product quality laid a solid foundation; To actively deal with technical barriers to trade, help enterprises to improve the level of quality management, quality control ability, and the wall response capacity, is of great guiding significance. At the same time for the country in the future research and develop 'green power', 'green appliances' and other related products technical measures and regulations provides a good first-hand resources.