在基于MCU的設(shè)計中有效地關(guān)閉控制回路

　　控制回路是許多基于MCU的設(shè)計中最基本的任務(wù)之一。通常這些設(shè)計中未充分利用的關(guān)鍵特征和外圍設(shè)備在現(xiàn)代單片機最有效地實現(xiàn)閉環(huán)控制系統(tǒng)。定時器和中斷控制器經(jīng)常使用在這些系統(tǒng)中，但一些其他功能，如DMA，先進(jìn)的模擬-數(shù)字轉(zhuǎn)換器，和專門的數(shù)學(xué)功能時，許多時候忽略了實施控制系統(tǒng)。

　　本文將快速審查的一些關(guān)鍵要求，高效的基于MCU的閉環(huán)控制系統(tǒng)。提高效率的常用技術(shù)將使用一些例子說明MCUs。一旦你了解了一些提高效率的常用技術(shù)，你可以更好地尋找實現(xiàn)你的下一個控制回路設(shè)計的最佳實現(xiàn)方法。

　　Control-loop basics

　　Control loops are key elements used in controlling dynamic systems. A dynamic system can be any mechanical or electrical system that has a relationship （typically modeled as a linear relationship） between the input and output. The output usually needs to be controlled in such a way as to stay within a desired operating “band”。 For example， the automatic cruise control in a car is such a system， where the speed of the car is set at a desired level and a controller keeps the speed constant even if the car encounters a hill. The algorithm that controls the speed utilizes a control loop that applies an input （the pressure on the accelerator）， measures the result （the speed） and adjusts the input as needed to maintain the speed at the desired level. A block diagram of a simple single input and single output control system， with a control loop， is shown in Figure 1 below.