SPI读SD卡文件系统

				/* filename: usart.c */
				#include "stm32f10x_lib.h"
				#include "usart.h"
				
				void USART_Config(void)
				{
				    GPIO_InitTypeDef GPIO_InitStructure;
				    USART_InitTypeDef USART_InitStructure;
				
				    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | 
				            RCC_APB2Periph_AFIO |
				            RCC_APB2Periph_USART1 , 
				            ENABLE);
				
				    /* Configure USART1_Tx as alternate function push-pull */
				    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
				    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
				    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
				    GPIO_Init(GPIOA, &GPIO_InitStructure);
				
				    /* Configure USART1_Rx as input floating */
				    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
				    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
				    GPIO_Init(GPIOA, &GPIO_InitStructure);
				
				    USART_InitStructure.USART_BaudRate = 115200;
				    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
				    USART_InitStructure.USART_StopBits = USART_StopBits_1;
				    USART_InitStructure.USART_Parity = USART_Parity_No ;
				    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
				    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
				
				    /* Configure the USARTx */ 
				    USART_Init(USART1, &USART_InitStructure);
				    /* Enable the USARTx */
				    USART_Cmd(USART1, ENABLE);
				}
				
				void USART1_Putc(unsigned char c)
				{
				    USART_SendData(USART1, c);
				    while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET );
				}
				
				void USART1_Puts(char * str)
				{
				    while(*str)
				    {
				        USART_SendData(USART1, *str++);
				        /* Loop until the end of transmission */
				        while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
				    }
				
				}