毕业设计论文_于单片机的数字PWM控制器设计与应用软件.doc

基于单片机的数字PWM控制器设计与应用软件 摘 要 基于C51单片机和PWM对LED亮度进行调节， STC89C52作为主控芯片，设置了手动控制。在手动控制时，通过两个按键输出不同的PWM占空比对LED的电流进行控制，从而实现了对光度的手动调节。51单片机本身是没有PWM接口的，本文是通过软件模拟PWM在一定的频率的方波中，调整高电平和低电平的占空比，即可实现LED灯亮度控制。PWM调节LED亮度是一种利用简单的数字脉冲反复开关白光LED驱动器的调光技术。系统只需要提供宽、窄不同的数字式脉冲，即可简单地实现改变输出电流从而调节白光LED的亮度。不管用Buck,Boost,Buck-Boost还是线性调节器来驱动LED。它们的共同思路都是用驱动电路来控制光的输出。一些应用只是简单地来实现“开”和“关”地功能，但是更多地应用需求是要基本从0到100%调节光的亮度。而且经常要有很高的精度。使用开关电路以相对于人眼识别力来说足够高的频率工作来改变光输出的平均值，即数字调光。使用脉冲宽度调制PWM来设置周期和占空度，可能是最简单的实现数字调光的方法，并且Buck调节器拓扑往往能够提供一个最好的性能。关键词 单片机，数字脉冲，占空比调节，驱动电路，LED亮度调节 ABSTRABecause C51SCM and PWM can regulate the brightness of the white light LED, STC89C5 as the DSP set up the manual control. During the process of the manual control, different PWM duty ratio output by two key regulate the electric current of LED so as to realize the manual control of the luminosity. As a matter of fact, C51SCM don’t have the interface. The control of the brightness of LED is realized by the software which simulating the situation that PWM adjust the duty ratio of the high level and the low level. PWM dimming is a technology which makes use of simple digital pulse so as to switch white LED drive repeatedly.For Buck, Boost, Buck-Boost or linear regulation to drive LED, their common ideas are using drive circuit to control the output of light. Some applications only achieve the “on” and “off” function simply. While more application demand that it can regulate the brightness of light from 0 to 100% and often have very high precision. Digital dimmer is the use of the switch circuit which works in a high frequency with respect to human recognition capacity to change the average of the light output. The use of pulse width modulation to set the cycle and duty ratio is probably the simplest method to realize digital dimming and Buck regulator topology can often provide the best performance.KEY WORDS: SCM, digital pulse, duty-cycle correction, driver circuit, regulation of LED brightness 目 录 TOC \