不完全手册，一本简单好用的arm编程知道书，教你不使用库函数也可以写出出色的程序- unsigned int i BYTE buffer[512] // file copy buffer FATFS fs // Work area (file system object) for logical drive FIL fsrc // file objects FRESULT res

a simple sample source code for deriving i2c by software. this is Arm sample