| LED display screen which developed quickly from 1980s around the world is a kindof new type of digital display media LED display screen composed by LED module or dotmatrix pixel unit, this new type of display media have many advantages such as longservice life, high reliability, high ability adapting to the environment, low cost, highcost-effective etc, so it apply in many domains such as securities trading, financial andcommercial bank propaganda, public cultural entertainment etc.The thesis designs an based on FPGA image display LED screen system. The datasource of this system is from the image displaying on the computer screen. Based on theway of LED display screen working, the system includes five parts: computer imagesource, decoding circuit, FPGA image data processing, LED driving circuit, LED displayscreen. The thesis designs two parts: decoding circuit and FPGA image data processing.After comparison of traditional VGA interface and DVI interface, the system usingDVI interface receives image data from computer graphic card, after decoding circuitwhich is based on IC TFP501 output image data which could be recognized by FPGA.The image data includes 24 bits mixed data of red, green, blue, enabling signal andsynchronous data, then processed by FPGA .The red, green, blue image data unit valuecorrespond LED conduction time. Using the pulse driving drive LED ,realizing the LEDdisplay screen 256 gray level through adjusting the duty cycle. Analysis the graydistortion problem of LED display screen composed by LED module and give a solutionand the correction gray matrix.The whole system includes six logic modules: image data acquisition module, imagedata format conversion module, gray level realizing module, SRAM module, conductiontime control module, clock control module, etc. The thesis introduces processing principleof each module, gives some modules’timing analysis. Some modules are downloaded tothe IC for testing and verifying by the EP2C8Q208C development board. |
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