How to Design and Implement Embedded Navigation System

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How to Design and Implement Embedded Navigation System [Copy link]

Digital geographic integrated applications and their corresponding solutions based on embedded systems as the main platform, that is, handheld and vehicle-mounted GPS global satellite navigation systems, can solve people's urgent needs. Based on the S3C2440A microprocessor and Win CE 5.0 embedded operating system, a reliable and practical embedded navigation system is designed, and the functions provided can meet people's needs in daily life at this stage.
　　1 Main components of embedded navigation system
　　The embedded navigation system consists of hardware layer, software layer and middle layer. The hardware layer is mainly composed of an embedded processor core control module, plus peripheral functional modules; the software layer is mainly composed of system software and application software, among which the system software mainly refers to the embedded operating system, and the application software realizes the control function of the controlled object; the middle layer is also called the board support package (BSP), which separates the upper-level software from the underlying hardware, so that the underlying driver of the system is independent of the hardware.
　　BSP is a board support package, which is a layer between the motherboard hardware and the operating system. It should be said that it is part of the operating system. The main purpose is to support the operating system so that it can run better on the hardware motherboard. BSP is relative to the operating system. Different operating systems correspond to BSPs with different definitions. For example, although the BSP of VxWorks and the BSP of Linux have the same functions for a certain CPU, the writing methods and interface definitions are completely different. Therefore, BSP must be written in accordance with the definition of the BSP of the system (most of the BSP programming process is to modify a certain BSP template). In this way, the correct interface with the upper-level OS can be maintained and the upper-level OS can be well supported.
　　2 Hardware Design of Embedded Navigation System
　　2.1 Overall Design of System Hardware
　　The hardware core of the embedded navigation system is the S3C2440A microprocessor. It is a RISC processor with the core of ARM920T. The external parts include: storage modules SDRAM, NAND FLASH, SD card; input modules include GPS module and matrix keyboard module; interface modules include: RS 232, USB. The hardware composition of GPS embedded navigation system is shown in Figure 1.

　　2.2 GPS core module circuit design
　　GPS is the abbreviation of Global Positioning System in English, and its Chinese abbreviation is "球位系". GPS is a new generation of space satellite navigation and positioning system jointly developed by the US Army, Navy and Air Force in the 1970s. Its main purpose is to provide real-time, all-weather and global navigation services for the three major areas of land, sea and air, and to be used for some military purposes such as intelligence collection, nuclear explosion monitoring and emergency communications. After more than 20 years of research and experiments, at a cost of 30 billion US dollars, by March 1994, 24 GPS satellite constellations with a global coverage rate of up to 98% had been deployed. In the field of machinery, GPS has another meaning: Geometrical Product Specifications - referred to as GPS. Another explanation is G/s (GBpers). The GPS receiver chip used in this navigation system is the iTrax300 GPS receiver chip of Fas-trax Company in Finland. iTrax 300 is an OEM GPS receiver chip with programmable NEMA protocol, featuring extremely low power consumption and minimal hardware design. The interface circuit between the module and S3C2440A is shown in Figure 2. Among them, RX_GPS and RX_GPS are connected to the UART port.
　

　　3 Embedded Navigation System Software Design
　　The system software consists of embedded system software (Win CE 5.0) and application software (GPS navigation software).
　　3.1 Construction of Win CE 5.0 Embedded Operating System
　　Windows CE is the foundation of Microsoft's embedded and mobile computing platform. It is an open and upgradeable 32-bit embedded operating system. It is an operating system for electronic devices based on handheld computers. It is a streamlined Windows 95. The graphical user interface of Windows CE is quite outstanding. WinCE 5.0 was launched in May 2004. Microsoft announced that WinCE 5.0 would expand the open source code. Under the authorization of this open source program, Microsoft opened 2.5 million lines of source code as an evaluation kit. All individuals and manufacturers can download these source codes for modification and use. In the future, when manufacturers OEM, they will pay a license fee of $3 per machine for the WinCE 5.0 core according to the Run-Time authorization. This is also the first operating system that Microsoft provides commercial derivative authorization.
　　3.2 Application software design under Win CE operating system
　　The application software is a navigation software application developed based on the win CE 5.0 embedded operating system, which is used to realize the control function of the controlled object. The navigation software needs to provide a friendly human-computer interface, and cooperate with the multi-functional electronic map to complete the analysis and positioning of the GPS signal; finally, the path planning and voice navigation functions are mapped to the hardware and software design process of the entire system. The design process of writing GPS navigation software under Embedded Visual C++4.0 is shown in Figure 3.
　

　　After the application software is edited, the ActiveSync connection between the PC and the embedded system is established, and the navigation software is ported to the Win CE 5.0 operating system. The final interface is shown in Figure 4. The user determines the current position based on the current position of the navigation software and enters the destination through the matrix keyboard. The navigation software can perform path planning and voice navigation.
　

　　4 Conclusion
　　This paper starts with hardware and software and briefly describes the entire design process of the embedded navigation system, involving the implementation of S3C2440A, WindowsCE5.0 and GPS modules in the system. The system can be used in handheld and vehicle-mounted satellite navigation systems, making people's daily travel more convenient and driving safer, and has broad application prospects.