51系列单片机读卡程序，本人亲测，适合考勤、门禁。

在PROTEUS仿真实现，在液晶显示器上显示采集温度的波形图-In the PROTEUS simulation, in the liquid crystal display to show temperature waveform acquisition

详细介绍了51单片机的指令系统，通过此文档进一步了解51单片机的体系结构-Detailed instructions for 51 single-chip system, the adoption of this document to learn more about 51 single-chip architecture

c8051f120_ad采样程序 ，很好用的-c8051f120_ad sampling procedures, well used

这个程序是用C语言写的基于I2C接口的驱动程序源代码-This procedure is written in C language interface based on the I2C driver source code

12864液晶（STC7920控制器）屏上用基本指令与扩充指令分时显示文字、图片、图片与文字混合、任意位置的图片。-12864 LCD (STC7920 controller) to use on-screen instructions and the expansion of the basic time-sharing display text instructions, pictures, images and characters mixed, arbitrary location of the picture.

使用Virelog编的一个pwm程序，简单易懂，适合初学者参考-Use Virelog compiled a pwm program, easy to understand for beginners reference

单片机实现传输的协议 -the agreement

基于8051F020,目的：用PCF8574器件实现并口输入，输出操作-Based on 8051F020, Objective: To realize parallel PCF8574 device input and output operation

用AD603提高超声波测距范围。超声波测距是一种非接触的测量方式，它是根据超声波从发射传感器到反射物体，再从反射物体到接收传感器的延迟时间.，利用距离/01. 2 ’，得到距离值，1 为声波在空气介质中的传播速度。由于反射超声波接收时的信号幅度与反射物体离接收传感器的距离远近有关，一般相差几十分贝-Ultrasonic Distance Measurement with the scope of AD603 improve. Ultrasonic Distance Measurement is a non-contact measurement, which is the ultrasonic sensor to the reflection from the launch of objects, objects from the reflector to the receiving sensor delay time., The use of distance/01.2, the distance values, one for the sound waves in air medium velocity. Receive as a result of reflection at the time of ultrasonic signal amplitude and the reflection from the object to receive the sensor distance, generally a difference of tens of decibels

一个4510的BIOS,已经测试通过了,在里面添加了基于USB的烧写方法-a BIOS 4510, has passed the test, they add a USB-based method of burning