| Embedded system is an application specific computer system. It is based on computer technology facing idiographic applications, and scalable on software and hardware. Embedded system is applied under the specific circumstances, which determines that it is strict with function, reliability, cost, size, power consumption, etc. The platform facing GPS (Global Positioning System) mobile terminal application implements fuctions such as position inquiry, wireless communication, audio and video, etc by combining GIS (Geographic Information System), GPS, GPRS (General Packet Radio Service), audio and video.A few theories are needed in embeded system design process. Embedded system architecture theory provides guideline to application, and circuit theory about high-speed system design provides design gist and technical support to design reliable hardware, and power theory ensures supply subsystem running well.The design includes hardware design and software design. The key of hardware design is processor circuit design. In addition, it integrates circuits such as ethernet, audio, video, USB (Universal Serial Bus), GPS, GPRS and etc. A few key problems are resolved by simulating at schematic level and singal integrity analyzing at board level. The key problems include crosstalk between signals, reflection on transmission line and impedance matching. In the process of dealing with effect of transmission line, whether signal impedance is matched or not is a vital factor to get optimal characteristic for design.Standardization of PCB (Printed Circuit Board) design process is important. Process standardization can make failure probability lowest for accidental factor. Summarizing experience how to build component footprint and concluding procedure of design ensures outputing files correctly.Software development includes download executable code, bootloader, operating system. After development of download executable code running on the host is completed, bootloader can be downloaded to bare board by serial line. Porting bootloader and operating system is succeeded on the basis. Bootloader boots system while passing necessary parameter to operating system. |
