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在设计微机实时控制系统时,常选用单板机作为系统的主机或前级机,这主要是由于单板机具有功能强、价格低的特点。然而在这类应用中也存在某些问题,例如,单板机的软件扫描显示方式在一些复杂的多任务实时系统中就难以适用,这是因为软件扫描显示要占用CPU较多的工作时间,而在这段时间内CPU又不能用作共它处理,这在系统的时序安排上容易发生某些冲突,影响系统运行的可靠性。同时还削弱了CPU的实时处理能力,尤其对某些实时性要求较高的连续过程控制系统,这种软件扫描显示方式的缺陷就更为明显。由于CPU的实时处理能力受单板机时钟频率的限制,而时钟频率又不能任意提高,所以在实时
In the design of real-time computer control system, the board is often used as a host of the system or front-end machine, which is mainly due to the single-board machine with strong features, low prices. However, there are also some problems in such applications. For example, the software scan display method of the single board computer is difficult to apply in some complicated multitasking real-time systems because the software scanning shows that it takes more working time of the CPU, In this period of time, the CPU can not be used as a total of its handling, which is prone to some conflicts in the timing of the system, affecting the reliability of system operation. But also weakened the CPU’s real-time processing capabilities, especially for some real-time requirements of continuous process control system, the software scan display is even more obvious flaw. Due to the CPU’s real-time processing capabilities by the single board machine clock frequency limit, and the clock frequency can not be arbitrarily increased, so in real time