| With the daily increased demand of embedded product, the embedded system also becomes increasingly complex. The traditional software and hardware respective development pattern causes the goal system resources optimization to be insufficient, the reliability, security and realtime are all with difficult safeguard, and the development cycle and the cost also come under the very tremendous influence. All above has been unable to satisfy the request of the modern embedded design. The HW/SW codesign method emerging in 90 ages has made up the traditional design method. Along with the deep research, it has been transformed the general rule into the mainstream technology in the embedded system. In so many existing codesign methods, the majority aim at the chip level embedded system of the SOC design, some methods owe larger spending at the system analysis stage, lower automated level, and smaller design cover scope; and some others owe larger spending in the algorithm design and the realization, higher sensitivity to the initial condition, and the worse actual design environment.Based on the problems above, first, this article analyzes the questions and the contradictions in the embedded system now, then points out the deficiency of the traditional embedded design and the predominance of the HW/SW codesign; finally indicates the superiority and the insufficiency of each kind of codesign method by the comparison of the existing codesign methods. This article proposes the system-level HW/SW codesign method called Dual-trees based on these methods above, which uses UML to describe the embedded system, and builds system behavior tree and resources tree by UML analysis. Through analyzing them, we can obtain the actual system architecture, discover the reasonable function way among the behavior nodes, and achieve the reasonable embedded system design scheme. Compared with the existing HW/SW codesign methods, this method defines more integrate resources class, fully considers the actual design environment, and owes the advantages of smaller spending of algorithm design and the realization, lower sensitivity to the initial condition, stronger actual utility and so on.In addition, under the instruction of Dual-trees method, this article detailedly analyzes one kind of typical embedded system—PDA, and carries on the development and the realization actually. The experimental result proves that this method plays a vital role from the PDA software and hardware selection to the reasonable design, reduces the PDA development cycle and enhances the PDA reliability and the performance-to-price ratio, which makes the adjustment and reuse in the PDA design scheme easily. Finally, this article carries on the comparison between the PDA systems designed by us to the existing PDA systems. This PDA system has the lower cost, higher reliable, multi-purpose and the user interface friendly and so on. In the intense competitive embedded market, these characteristics will be more significant day by day. |
