Research Of LED Display Screen System Based On GPRS And CPLD

LED display screen is a kind of planar display screen which consists of light-emitting diode modules or pixel units. Compared with other display mediums, LED display screen has some unique advantages such as long-term durability, high brightness, large angle of visibility, flexible configuration, abundant colors and so on, so it's widely used in advertising media, information dissemination, decorative lighting and other fields. LED display screen brings large amounts of information as well as a fresh experience to people.With the widening of the application field's requirements, some LED display screen systems need to improve the way of data transmission, the approach and the rate to refresh the screen. To meet the new needs, some systems have to overcome their shortcomings such as low efficiency of MCU, low speed and short distance and low reliability of data transmission, low rate of static scanning and so on. According to these actual demands and the analysis of the system's requirements of the MCU, data transfer and the scanning circuit, the LED display screen system based on GPRS and CPLD is proposed.The MCU of the system is PXA270 processor based on the XScale core. It translates and stores the information received from a PC or a mobile phone. Video data is transferred between PC and the display controller via Ethernet. In addition, the system is also equipped with a GPRS/GSM module by which users can modify the video information anytime and anywhere they like. The control circuit consisting of CPLD scans the screen dynamically by area and renews the display information. With the light intensity data of the external environment collected by a photoresistor, the system is able to adjust the brightness of the screen.The experiments indicate that the MCU of the system is high-performance. With the Ethernet, the speed and distance and reliability of the system's data transmission has been improved a lot. The GPRS keeps the data transmission away from interference, and it is convenient for users to modify the video information. The system has simplified the scanning circuit and improved the refresh rate. It can display characters of different fonts and different sizes as well as pictures. The system is capable of adjusting the brightness of the screen automatically, so it is able to save energy and reduce consumption, and it achieves an excellent visual effect.