本例使用了8位的电流型D/A转换器DAC0808及运算放大器，运行本例时，按下k1~k8

中的某个按键，单片机会向数模转换芯片输出0x00~0xFF之间的8个不同数值，经转换后会输出8档不同电压。程序对8个按键进行独立定义，按下不同按键时向D/A转换芯片 不同字节，从而输出8档不同的电压。

读者在调试本例后，可修改程序，用其中2个按键增减电压，其余按键用于实现不同的精度调节设置（如0.1，0.01，0.001等），实现更加精确的数字控制电压输出。-This example uses the 8-bit current-type D/A converter DAC0808 and operational amplifiers, run this example, press the k1 ~ k8 a button, the microcontroller will be output to the digital-analog converter chip between 8 0x00 ~ 0xFF different values, after converting the file will be 8 different output voltages. Program for eight key independent definition of the D/A converter chip different bytes, so that the output voltage of 8 different files when you press a different key. In this case, the reader debugging, you can modify the program, with one of two buttons increase or decrease the voltage, the rest of the keys used to achieve different accuracy adjust settings (such as 0.1, 0.01, etc.), to achieve a more precise digital control voltage output.