Embedded Systems, Graphics Design And Realization

Since 1990s,embedded systems have won great success from computer controlling industry because of non-monopoly and cost-efficiency. The system substituted kinds of MCU for CPU, flash memory and SRAM/SDRAM for ROM, RAM and hard disc, embedded operating system for Window, DOS in general-purpose computer. It is irreversible that embedded system would take place of general-purposed computer in computer customization domain. Compared with other kinds of monitors, LCD is small, light, and low radiation so that it is the optimal choice up to date. To apply LCD in embedded system for man-machine conversation, the ordinary methods are MCU driven and FPGA driven. Both methods, however, are requiring a great deal of time of MCU that impeded the principal function of controlling the automatic equipment. A FPGA centered graphic card for embedded system is proposed in the dissertation to solve the problem.Taking single DDR SDRAM as graphic memory and FPGA as control core, the graphic card only demands just a frame's data when changing the picture on the screen rather than continuous data flow and real-time control signals, so that the embedded system can release more resource on automatic controlling.To begin with PCB, I/O standard compatibility and interface problems are solved, then LCM driven circuit such as bipolar driven voltage circuit and buffering circuit are designed as well. Based on the PCB, the project has been designed.Since the multi-clock-domain characteristic and DDR SDRAM driven demand, the project built the system with data channel module and data control module; Separating clock domain with data buffering module, synchronized design of data crossing clock domains has been researched and accomplished; by allocating read/wite time appropriately, DDR SDRAM control module has set to drive memory chip.Using 800×480 resolution LCD as graphic ouput device, the display system can input data flow below 50MHz with general MCU interface. To verify the result, test system was designed centred with EasyARM2131 since independent system has no image source. When MCU output data changed, the image on the screen was changed gradually, which indicates the project has achieved the anticipation.