键盘状态扫描函数
/*
键盘扫描函数
读取当前键盘的状态
有按键按下返回相应按键值
无按键按下返回"0x00"
*/
-Keyboard status scan function/* keyboard scan function to read the current state of the keyboard keys have a corresponding button press to return to the value of non-button press to return to
三星CPUS3C2440,SMDK2440 USB downloader firmware代码,通过USB下载文件到FLASH-Samsung CPUS3C2440, SMDK2440 USB downloader firmware code, through the USB to download files to the FLASH