环境光自适应LED显示屏设计.doc

摘 要 随着LED显示屏技术的成熟、成本降低、以及安装使用方便等特点，LED显示屏得到了越来越广泛的应用。由于LED显示亮度不随外界环境光而改变，存在白天显示不清或黑夜因太亮而炫目的问题。设计一个环境光自适应LED显示屏具有实际的意义。 本文介绍一种实现LED显示屏随着环境的光照强度改变其亮度的控制系统。该系统以STC89C52单片机为主控制器，使用电流型传感器ON9658对环境光照强度进行采集，通过AD0809模数转换器将采集到的数据进行转换，送到单片机进行处理。通过采样值判断8*8LED显示屏亮度，避免了白天显示不清或黑夜因太亮而炫目。单片机采用全局使能PWM方法控制脉宽的调制方法来实现LED显示屏亮度控制，也就是周期性改变电流脉冲宽度(即占空比)从而改变改变LED灯管的平均电流，从而改变显示屏的亮度。该设计实现了自动调整LED显示屏亮度和人为手工调节其亮度的功能，并且能够显示LED显示屏的亮度值。 文中介绍了系统的设计方案和工作原理，详细阐述了系统各个模块（单片机控制模块、光照强度采集模块、数据处理模块、驱动模块等）的软硬件实现方法，包括主要元器件介绍；电路模块的设计说明；软件设计流程。文中提供了测试数据，总结了系统实现的功能，分析出不足，并提出了展望。 关键词：STC89C51单片机；环境光自适应；PWM；LED显示屏；ON9658 Abstract With the maturity of the LED（light emitting diode）display technology, cost reduction, as well as to install and easy to use features, LED display has been widely used. As the LED display brightness does not vary with outside ambient light changes, there are daytime show is unclear or night due to too bright and dazzling, the design of an Ambient Light Adaptive LED display real meaning. This paper describes a LED display to change its brightness with the light intensity of the environment control system. The system controller mainly to STC89C52 microcontroller, using the current sensor ON9658 collection of ambient light intensity, will be collected by the AD0809 analog-to-digital converter to convert the data sent to the microcontroller for processing. 8 * 8LED display brightness by sampling the value judgment to avoid the daytime show is unclear or night due to too bright and dazzling. Microcontrollers in the global enable PWM control pulse width modulation method to achieve the LED display brightness control, cyclical changes in the current pulse width (duty cycle) to change to change the average current of the LED lamp, thereby changing the display brightness. The design automatically adjust the LED display brightness and man-made manually adjusting the brightness, and be able to display the value of the brightness of the LED display. This paper describes the design and working pr