s3c2440的裸板程序，基于KEIL4的工程文件，内容有串口驱动，LED灯驱动，蜂鸣器驱动，中断程序，拷贝程序到内存的代码，MMU映射代码。大部分用arm汇编实现-S3C2440-UART Driver、BEEP Driver、LED Light Driver、ISR program、MMU program

利用PWM来驱动蜂鸣器，脉宽从低到高，再从高到低，周而复始。我们还利用4个LED来指示频率的高低，最高时LED全亮，最低时LED全灭。-PWM to drive the buzzer, the pulse width from low to high to low again, and again and again. We also use four LEDs to indicate the level of frequency, the maximum full-bright LED low