在你的MCU上运行RTOS时的硬件考虑

　　在你的MCU上运行RTOS时的硬件考虑

　　MCU来控制嵌入式系统在越来越多的功能。通常这些功能是实时的，需要定期的服务，以满足系统的要求，响应，性能，或可靠性。通常，实时操作系统（RTOS）用于管理多个实时事件，以确保响应速度足以满足系统要求。不是所有的MCU都适合举办一个实时操作系统，然而，所以回顾一些关键功能，允许或促进主机实时操作系统在一个特定的单片机的实时嵌入式系统的设计者很有用。

　　本文将回顾一些可用的关键特征对现代MCUs，帮助运行嵌入式系统需要实时操作系统时。这将有助于设计人员更有效地选择一个MCU作为一个RTOS主机，并设计使用该MCU的嵌入式系统。

　　Managing real-time response

　　As control systems become more complicated， it is increasingly difficult to manage the various MCU functions with a simple control routine. With multiple events with different priorities， a single control loop that is constantly checking to see what event needs service becomes unwieldy. The control loop just cannot get to every function quickly enough. What is needed is a real-time approach to control， where all events can be serviced within their required response time.

　　Often an MCU can achieve better control over complex systems by responding to an event， either an internal MCU request triggered by a timer or an external event triggered by an I/O signal， using an interrupt. Interrupts can be prioritized so that the most important requests are processed first， and with modern MCU interrupt systems， response times can be very fast. Unfortunately， proving that all events will be handled with the required periodicity can be difficult. For example， if we need to make a series of analog-to-digital conversions， while receiving data over a USB port and computing a low-pass filter on the acquired analog data， figuring out the maximum sample rate for the conversion may be very difficult.