51单片机在编程电路中的应用

51单片机在编程电路中的应用(中文4500字,英文3000字)
本应用指南说明了Atmel AT89C51是可在线可编程的微控制器。它为电路编程提出了相应的例子，程序的修改需要在线编程的支持。这类显示方法在应用程序中的AT89C51单片机可通过电话线远程控制。该应用指南所描述的电路只支持5v电压下编程。此应用软件可以到Atmel进行下载。
总论
当不在进行程序设计的时候，在电路设计中的AT89C51设计将变得透明化。
在编程期间必须重视EA/VPP这一脚。在不使用外部程序存储器的应用程序中，这脚可能会永久接到VCC。应用程序使用的外部程序存储器要求这一脚为低电平才能正常运行。
AT89C51 In-Circuit Programming
This application note illustrates the in-circuit programmability of the Atmel AT89C51 Flash-based microcontroller. Guidelines for the addition of in-circuit programmability to AT89C51 applications are presented along with an application example and the modifications to it required to support in-circuit programming. A method is then shown by which the AT89C51 microcontroller in the application can be reprogrammed remotely, over a commercial  telephone line. The circuitry described in this application note supports five volt programming only, requiring the use of an AT89C51-XX-5. The standard AT89C51 requires 12 volts for programming. The software for this application may be obtained by downloading from Atmel’s