STM32之独立版USB(Host)驱动+MSC+Fatfs移植

写在前面

现在，网上关于STM32的USB的文章数不胜数。写这篇文章仅仅是对于自我学习的一个记录。主要是对实际学习中遇到的一些棘手问题做个备忘录。使用的芯片为STM32F407VG 。
目前，ST的USB驱动有两套，一套是早期的独立版USB驱动，最新版为2.2.0；一套为针对其Cube系列的驱动，根据芯片不同可能有区别，具体见对应芯片的Cube驱动包。 本文使用的为独立版USB驱动。即：HAL库+独立版USB库
目前，Fatfs 驱动最新版为R0.13a 。
本文多出自于ST的官方文档，读者也可以直接去ST官网查阅相关文档。
本文主要涉及USB Host（全速）+ MSC + Fatfs的移植。其他移植后续用到再说。
关于独立版USB驱动库的详解见 http://blog.csdn.net/zcshoucsdn/article/details/78936456

USB驱动部分

源码移植

源码的移植相对来说比较简单，使用时，根据需要复制相关的文件即可。需要注意的是，整理一下源码的结构。这个在上一篇博文中已经由说明了。具体见下图：
USB Host
在移植其他部分的时候与之类似，只需要替换成对应部分的源码文件即可。

源码中的 USB OTG部分是所有其他模块的驱动程序。

usbh_msc_fatfs.c为ST提供的FatFs的diskio.c的具体实现文件。在使用了该文件后，用户不必再自行实现FafFs的diskio.c了。

源码配置

整个USB驱动用于灵活的配置选项，且通过一个配置文件的形式给出。这样，使用者可以尽量少的修改的驱动源代码。这些配置文件均为用户级别的文件，通常来说置于用户代码目录下。如下如所示：
USBHostUser
作为用户级文件，通常所有的用户代码均在以上文件做修改即可，只有少数特殊处理会设计到驱动程序源码的修改。在配置好后，一般来说，所有修改均在usbh_usr.h/.c中。

usb_config.h

usb_config.h是USB OTG 底层驱动的配置文件。在USB OTG的源代码中，ST提供了usb_conf_template.h。使用者只需要复制该文件到自己的代码目录下，修改即可。具体配置见下文的注释部分：

/**  ******************************************************************************
  * @file    usb_conf.h
  * @author  
  * @version V2.2.0
  * @date    2017.12.27
  * @brief   USB的底层驱动配置
 ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2017 ST</center></h2>
  *
  * 
 ******************************************************************************
  */
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __USB_CONF__H__
#define __USB_CONF__H__

/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"      /* 这里需要包含自己使用的ST的库的头文件 */
/** @addtogroup USB_OTG_DRIVER
  * @{
  */
/** @defgroup USB_CONF
  * @brief USB 底层驱动配置文件
  * @{
  */ 
/** @defgroup USB_CONF_Exported_Defines
  * @{
  */ 
/* USB Core and PHY interface 配置.
   Tip: To avoid modifying these defines each time you need to change the USB configuration, you can declare the needed define in your toolchain compiler preprocessor.
   */
/**** 配置文件包含了Full Speed 和 High Speed 两种速率的配置，使用时，从两者选择其一即可。****/
/****************** USB OTG FS PHY 配置 *******************************
*   USB OTG FS Core 支持 one on-chip Full Speed PHY。通常，ST芯片内部已经集成了该PHY。
*  
*  当使用了FS core时，宏USE_EMBEDDED_PHY 需要在编译器中定义.
*  
*******************************************************************************/
#ifndef USE_USB_OTG_FS
    #define USE_USB_OTG_FS                      /* 使用 FS， 与下面的 HS 只能选一个。目前，终端只支持FS */
#endif /* USE_USB_OTG_FS */

#ifdef USE_USB_OTG_FS 
    #define USB_OTG_FS_CORE
#endif
/****************** USB OTG HS PHY 配置 *******************************
*  USB OTG HS Core 支持 两种 PHY 接口:
*   (i)  使用外部高速PHY的ULPI 接口:  USB HS Core 工作在高速模式下
*   (ii) 片内Full Speed PHY: USB HS Core 工作在全速模式下
*  通过下面两个宏，选择使用哪种PHY:
*   (i)  USE_ULPI_PHY: if the USB OTG HS Core is to be used in High speed mode 
*   (ii) USE_EMBEDDED_PHY: if the USB OTG HS Core is to be used in Full speed mode
*
*  Notes: 
*   - The USE_ULPI_PHY symbol is defined in the project compiler preprocessor as default PHY when HS core is used.
*   - On STM322xG-EVAL and STM324xG-EVAL boards, only configuration(i) is available.
*     Configuration (ii) need a different hardware, for more details refer to your  STM32 device datasheet.
*******************************************************************************/
#ifndef USE_USB_OTG_HS
    //#define USE_USB_OTG_HS
#endif /* USE_USB_OTG_HS */

#ifndef USE_ULPI_PHY
    //#define USE_ULPI_PHY
#endif /* USE_ULPI_PHY */

#ifndef USE_EMBEDDED_PHY
    //#define USE_EMBEDDED_PHY
#endif /* USE_EMBEDDED_PHY */

#ifdef USE_USB_OTG_HS 
    #define USB_OTG_HS_CORE
#endif

/*******************************************************************************
*                      FIFO Size Configuration in Device mode
*  
*  (i) Receive data FIFO size = RAM for setup packets + 
*                   OUT endpoint control information +
*                   data OUT packets + miscellaneous
*      Space = ONE 32-bits words
*     --> RAM for setup packets = 10 spaces
*        (n is the nbr of CTRL EPs the device core supports) 
*     --> OUT EP CTRL info      = 1 space
*        (one space for status information written to the FIFO along with each 
*        received packet)
*     --> data OUT packets      = (Largest Packet Size / 4) + 1 spaces 
*        (MINIMUM to receive packets)
*     --> OR data OUT packets  = at least 2*(Largest Packet Size / 4) + 1 spaces 
*        (if high-bandwidth EP is enabled or multiple isochronous EPs)
*     --> miscellaneous = 1 space per OUT EP
*        (one space for transfer complete status information also pushed to the 
*        FIFO with each endpoint's last packet)
*
*  (ii)MINIMUM RAM space required for each IN EP Tx FIFO = MAX packet size for 
*       that particular IN EP. More space allocated in the IN EP Tx FIFO results
*       in a better performance on the USB and can hide latencies on the AHB.
*
*  (iii) TXn min size = 16 words. (n  : Transmit FIFO index)
*   (iv) When a TxFIFO is not used, the Configuration should be as follows: 
*       case 1 :  n > m    and Txn is not used    (n,m  : Transmit FIFO indexes)
*       --> Txm can use the space allocated for Txn.
*       case2  :  n < m    and Txn is not used    (n,m  : Transmit FIFO indexes)
*       --> Txn should be configured with the minimum space of 16 words
*  (v) The FIFO is used optimally when used TxFIFOs are allocated in the top 
*       of the FIFO.Ex: use EP1 and EP2 as IN instead of EP1 and EP3 as IN ones.
*******************************************************************************/

/*******************************************************************************
*                     FIFO Size Configuration in Host mode
*  
*  (i) Receive data FIFO size = (Largest Packet Size / 4) + 1 or 
*                             2x (Largest Packet Size / 4) + 1,  If a 
*                             high-bandwidth channel or multiple isochronous 
*                             channels are enabled
*
*  (ii) For the host nonperiodic Transmit FIFO is the largest maximum packet size 
*      for all supported nonperiodic OUT channels. Typically, a space 
*      corresponding to two Largest Packet Size is recommended.
*
*  (iii) The minimum amount of RAM required for Host periodic Transmit FIFO is 
*        the largest maximum packet size for all supported periodic OUT channels.
*        If there is at least one High Bandwidth Isochronous OUT endpoint, 
*        then the space must be at least two times the maximum packet size for 
*        that channel.
*******************************************************************************/

/****************** USB OTG HS CONFIGURATION **********************************/
/* 以下暂不使用 */
#ifdef USB_OTG_HS_CORE
    #define RX_FIFO_HS_SIZE                          512    /* 设置高速内核的接收FIFO大小。*/
    /* 设置设备端点的发送FIFO大小（高速），其中0~3是要使用的端点的索引。*/
    #define TX0_FIFO_HS_SIZE                         512
    #define TX1_FIFO_HS_SIZE                         512
    #define TX2_FIFO_HS_SIZE                          0
    #define TX3_FIFO_HS_SIZE                          0
    #define TX4_FIFO_HS_SIZE                          0
    #define TX5_FIFO_HS_SIZE                          0
    #define TXH_NP_HS_FIFOSIZ                         96    /* 设置主机模式（高速）的非周期性发送FIFO大小。 */
    #define TXH_P_HS_FIFOSIZ                          96    /* 设置主机模式（高速）的周期性发送FIFO大小。*/

//  #define USB_OTG_HS_LOW_PWR_MGMT_SUPPORT     /* 实现高速核心（USB核心时钟门控等）的低功耗管理。 */
//  #define USB_OTG_HS_SOF_OUTPUT_ENABLED

//  #define USB_OTG_INTERNAL_VBUS_ENABLED
    #define USB_OTG_EXTERNAL_VBUS_ENABLED

    #ifdef USE_ULPI_PHY
        #define USB_OTG_ULPI_PHY_ENABLED    /* 启用高速内核的ULPI PHY。 */
    #endif
    #ifdef USE_EMBEDDED_PHY
        #define USB_OTG_EMBEDDED_PHY_ENABLED    /* 为高速内核启用嵌入式FS PHY。 */
    #endif
    #define USB_OTG_HS_INTERNAL_DMA_ENABLED    /* 启用高速内核的内部DMA功能。 */
    #define USB_OTG_HS_DEDICATED_EP1_ENABLED    /* 在高速内核中为器件模式启用专用的端点1功能。 */
#endif

/****************** USB OTG FS CONFIGURATION **********************************/
#ifdef USB_OTG_FS_CORE
    #define RX_FIFO_FS_SIZE                          128    /* 设置全速内核的接收FIFO大小。 */
    /* 设置设备端点的发送FIFO大小（全速），其中0~3是要使用的端点的索引。*/
    #define TX0_FIFO_FS_SIZE                          64    
    #define TX1_FIFO_FS_SIZE                         128
    #define TX2_FIFO_FS_SIZE                          0
    #define TX3_FIFO_FS_SIZE                          0
    #define TXH_NP_FS_FIFOSIZ                         96    /* 设置主机模式（全速）的非周期性发送FIFO大小。 */
    #define TXH_P_FS_FIFOSIZ                          96    /* 设置主机模式（全速）的周期性发送FIFO大小。*/

//  #define USB_OTG_FS_LOW_PWR_MGMT_SUPPORT    /* 实现全速核心（USB核心时钟门控等）的低功耗管理。 */
//  #define USB_OTG_FS_SOF_OUTPUT_ENABLED
#endif

/****************** USB OTG MISC CONFIGURATION ********************************/
//#define VBUS_SENSING_ENABLED

/****************** USB OTG MODE CONFIGURATION ********************************/
#define USE_HOST_MODE                           /* 采用 Host 模式 与下面的 USE_DEVICE_MODE 和 USE_OTG_MODE 任选其一 */
//#define USE_DEVICE_MODE
//#define USE_OTG_MODE

#ifndef USB_OTG_FS_CORE
    #ifndef USB_OTG_HS_CORE
        #error  "USB_OTG_HS_CORE or USB_OTG_FS_CORE should be defined"
    #endif
#endif

#ifndef USE_DEVICE_MODE
    #ifndef USE_HOST_MODE
        #error  "USE_DEVICE_MODE or USE_HOST_MODE should be defined"
    #endif
#endif

#ifndef USE_USB_OTG_HS
    #ifndef USE_USB_OTG_FS
        #error  "USE_USB_OTG_HS or USE_USB_OTG_FS should be defined"
    #endif
#else //USE_USB_OTG_HS
    #ifndef USE_ULPI_PHY
        #ifndef USE_EMBEDDED_PHY
             #error  "USE_ULPI_PHY or USE_EMBEDDED_PHY should be defined"
        #endif
    #endif
#endif

/****************** C Compilers dependant keywords ****************************/
/* In HS mode and when the DMA is used, all variables and data structures dealing
   with the DMA during the transaction process should be 4-bytes aligned */    
#ifdef USB_OTG_HS_INTERNAL_DMA_ENABLED
  #if defined   (__GNUC__)        /* GNU Compiler */
    #define __ALIGN_END    __attribute__ ((aligned (4)))
    #define __ALIGN_BEGIN         
  #else                           
    #define __ALIGN_END
    #if defined   (__CC_ARM)      /* ARM Compiler */
      #define __ALIGN_BEGIN    __align(4)  
    #elif defined (__ICCARM__)    /* IAR Compiler */
      #define __ALIGN_BEGIN 
    #elif defined  (__TASKING__)  /* TASKING Compiler */
      #define __ALIGN_BEGIN    __align(4) 
    #endif /* __CC_ARM */  
  #endif /* __GNUC__ */ 
#else
  #define __ALIGN_BEGIN
  #define __ALIGN_END   
#endif /* USB_OTG_HS_INTERNAL_DMA_ENABLED */

/* __packed keyword used to decrease the data type alignment to 1-byte */
#if defined (__CC_ARM)         /* ARM Compiler */
  #define __packed    __packed
#elif defined (__ICCARM__)     /* IAR Compiler */
  #define __packed    __packed
#elif defined   ( __GNUC__ )   /* GNU Compiler */                        
  #define __packed    __attribute__ ((__packed__))
#elif defined   (__TASKING__)  /* TASKING Compiler */
  #define __packed    __unaligned
#endif /* __CC_ARM */

/**
  * @}
  */ 
  /*省略*/
#endif //__USB_CONF__H__
/**
  * @}
  */ 
/**
  * @}
  */ 
/************************ (C) COPYRIGHT  *****END OF FILE****/

usbh_config.h

usbh_config.h是USB Host 底层驱动的配置文件。在USB OTG的源代码中，ST提供了usbh_conf_template.h。使用者只需要复制该文件到自己的代码目录下，修改即可。具体配置见下文的注释部分：

/**
 ******************************************************************************
  * @file    usbh_conf.h
  * @author  
  * @version V2.2.0
  * @date    2017.12.27
  * @brief   USB Host library 配置
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2017 </center></h2>
  *
 ******************************************************************************
  */
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __USBH_CONF__H__
#define __USBH_CONF__H__
/* Includes ------------------------------------------------------------------*/
// #include "xxx.h"    /* 包含自己的各种头文件*/
/** @addtogroup USBH_OTG_DRIVER
  * @{
  */
/** @defgroup USBH_CONF
  * @brief USB Host 底层驱动配置文件
  * @{
  */
/** @defgroup USBH_CONF_Exported_Defines
  * @{
  */
#define USBH_MAX_NUM_ENDPOINTS              2           /* 支持端点的最大数量 1 bulk IN + 1 bulk Out */
#define USBH_MAX_NUM_INTERFACES             2           /* 支持接口的最大数量 */

#ifdef USE_USB_OTG_FS
    #define USBH_MSC_MPS_SIZE               0x40
#else
    #define USBH_MSC_MPS_SIZE               0x200
#endif
#define USBH_MAX_DATA_BUFFER                0x400

/* 错误信息打印函数 重定向 这里需要注意：该库使用了LCD_ErrLog，需要进行重定向，否则报错 */
/* 感觉 库直接将 其改名为 USB_Log 或者 USB_ErrLog 最好了 */
#define LCD_ErrLog(str)    udwComSendData(COM_CONSOLE, str, strlen(str));

/*  与Fatfs对接使用 */
#define _USE_IOCTL                          1
/**
  * @}
  */
/** @defgroup USBH_CONF_Exported_Types
  * @{
  */
/**
  * @}
  */
/** @defgroup USBH_CONF_Exported_Macros
  * @{
  */
/**
  * @}
  */
/** @defgroup USBH_CONF_Exported_Variables
  * @{
  */
/**
  * @}
  */
/** @defgroup USBH_CONF_Exported_FunctionsPrototype
  * @{
  */
/**
  * @}
  */

#endif //__USBH_CONF__H__

/**
  * @}
  */
/**
  * @}
  */
/************************ (C) COPYRIGHT  *****END OF FILE****/

usbh_bsp.c

包含（在USB OTG低级驱动程序的usb_bsp.h文件中声明）来初始化GPIO的核心，延时方法和中断启用/禁用的函数的实现。在USB OTG的源代码中，ST提供了usb_bsp_template.c。使用者只需要复制该文件到自己的代码目录下，修改即可。具体需要实现的函数在usb_bsp.h中已经定义好了，使用者不能更改接口名。见下文的注释部分：

void USB_OTG_BSP_Init (USB_OTG_CORE_HANDLE *pdev);    /* 该接口中 实现 USB Host 使用的各种 GPIO等*/
void USB_OTG_BSP_uDelay (const uint32_t usec);      /* USB 使用的延时函数 */
void USB_OTG_BSP_mDelay (const uint32_t msec);    /* USB 使用的延时函数 */
void USB_OTG_BSP_EnableInterrupt (USB_OTG_CORE_HANDLE *pdev);    /* USB 使用的中断 */
void USB_OTG_BSP_TimerIRQ (void);
/* 以下主要是用于 高速模式下的配置，如VBUS的过流检测等 */
#ifdef USE_HOST_MODE
void USB_OTG_BSP_ConfigVBUS(USB_OTG_CORE_HANDLE *pdev);
void USB_OTG_BSP_DriveVBUS(USB_OTG_CORE_HANDLE *pdev,uint8_t state);
void USB_OTG_BSP_Resume(USB_OTG_CORE_HANDLE *pdev);
void USB_OTG_BSP_Suspend(USB_OTG_CORE_HANDLE *pdev);
#endif /* USE_HOST_MODE */

usbh_usr.c/.h

包含（在USB库的usbh_usr.h文件中声明）来处理来自用户层（事件消息）的库事件的函数实现。需要实现的函数接口（注意：以下是针对MSC的，其他如HID的用户接口是不同的）见下文：

void USBH_USR_Init(void);
void USBH_USR_DeInit(void);
void USBH_USR_DeviceAttached(void);
void USBH_USR_ResetDevice(void);
void USBH_USR_DeviceDisconnected (void);
void USBH_USR_OverCurrentDetected (void);
void USBH_USR_DeviceSpeedDetected(uint8_t DeviceSpeed); 
void USBH_USR_Device_DescAvailable(void *);
void USBH_USR_DeviceAddressAssigned(void);
void USBH_USR_Configuration_DescAvailable(USBH_CfgDesc_TypeDef * cfgDesc,
                                          USBH_InterfaceDesc_TypeDef *itfDesc,
                                          USBH_EpDesc_TypeDef *epDesc);
void USBH_USR_Manufacturer_String(void *);
void USBH_USR_Product_String(void *);
void USBH_USR_SerialNum_String(void *);
void USBH_USR_EnumerationDone(void);
USBH_USR_Status USBH_USR_UserInput(void);
void USBH_USR_DeviceNotSupported(void);
void USBH_USR_UnrecoveredError(void);
int USBH_USR_MSC_Application(void);

对于MSC，使用以下回调：USBH_USR_MSC_Application()。在类初始化结束之后，这个函数被MSC状态机调用，以便向用户提供文件系统访问操作。使用者最终需要在该函数中实现自己的用户代码。在此回调中，用户可以使用FAT FS文件系统API实现对FAT文件系统的任何访问（文件打开，文件读取，文件写入…）。用户还可以访问从库MSC类驱动程序导出的结构变量：USBH_MSC_Param。
其他接口是这个USB Host 状态机一步一步执行过程的函数。使用者可以在不同的步骤添加对应的处理。最终，使用类型USBH_Usr_cb_TypeDef，将所有函数注册进USB Host驱动。

/* USB Host 用户接口 类型定义 */
typedef struct _USBH_USR_PROP
{
  void (*Init)(void);       /* HostLibInitialized */
  void (*DeInit)(void);       /* HostLibInitialized */  
  void (*DeviceAttached)(void);           /* DeviceAttached */
  void (*ResetDevice)(void);
  void (*DeviceDisconnected)(void); 
  void (*OverCurrentDetected)(void);  
  void (*DeviceSpeedDetected)(uint8_t DeviceSpeed);          /* DeviceSpeed */
  void (*DeviceDescAvailable)(void *);    /* DeviceDescriptor is available */
  void (*DeviceAddressAssigned)(void);  /* Address is assigned to USB Device */
  void (*ConfigurationDescAvailable)(USBH_CfgDesc_TypeDef *,
                                     USBH_InterfaceDesc_TypeDef *,
                                     USBH_EpDesc_TypeDef *); 
  /* Configuration Descriptor available */
  void (*ManufacturerString)(void *);     /* ManufacturerString*/
  void (*ProductString)(void *);          /* ProductString*/
  void (*SerialNumString)(void *);        /* SerialNubString*/
  void (*EnumerationDone)(void);           /* Enumeration finished */
  USBH_USR_Status (*UserInput)(void);
  int  (*UserApplication) (void);
  void (*DeviceNotSupported)(void); /* Device is not supported*/
  void (*UnrecoveredError)(void);

}
USBH_Usr_cb_TypeDef;
/* USB Host 用户接口 使用示例 */
USBH_Usr_cb_TypeDef USR_cb =
{
    USBH_USR_Init,
    USBH_USR_DeInit,
    USBH_USR_DeviceAttached,
    USBH_USR_ResetDevice,
    USBH_USR_DeviceDisconnected,
    USBH_USR_OverCurrentDetected,
    USBH_USR_DeviceSpeedDetected,
    USBH_USR_Device_DescAvailable,
    USBH_USR_DeviceAddressAssigned,
    USBH_USR_Configuration_DescAvailable,
    USBH_USR_Manufacturer_String,
    USBH_USR_Product_String,
    USBH_USR_SerialNum_String,
    USBH_USR_EnumerationDone,
    USBH_USR_UserInput,
    USBH_USR_MSC_Application,
    USBH_USR_DeviceNotSupported,
    USBH_USR_UnrecoveredError
};

注意事项

一旦使用了DMA( 高速模式下)，所有结构体必须是四字节对齐的。
如下即可使用 USB Host

/* 定义 USB_OTG_Core */
#ifdef USB_OTG_HS_INTERNAL_DMA_ENABLED
  #if defined ( __ICCARM__ ) /*!< IAR Compiler */
    #pragma data_alignment=4   
  #endif
#endif /* USB_OTG_HS_INTERNAL_DMA_ENABLED */
__ALIGN_BEGIN USB_OTG_CORE_HANDLE      USB_OTG_Core __ALIGN_END;
/* 定义 USB_Host */
#ifdef USB_OTG_HS_INTERNAL_DMA_ENABLED
  #if defined ( __ICCARM__ ) /*!< IAR Compiler */
    #pragma data_alignment=4   
  #endif
#endif /* USB_OTG_HS_INTERNAL_DMA_ENABLED */
__ALIGN_BEGIN USBH_HOST                USB_Host __ALIGN_END;

/****注意：在非启用到了DMA的高速模式下， 以上两个定义可直接简化（不需要对齐处理）如下：
* USB_OTG_CORE_HANDLE      USB_OTG_Core;
* USBH_HOST                USB_Host;
****/

/* 初始化 USB Host 库 */
USBH_Init( &USB_OTG_Core, 
#ifdef USE_USB_OTG_FS  
    USB_OTG_FS_CORE_ID,
#else 
    USB_OTG_HS_CORE_ID,
#endif 
    &USB_Host,
    &USBH_MSC_cb, 
    &USR_cb );

/* 最后，周期调用以下函数即可 */
USBH_Process(&USB_OTG_Core, &USB_Host);

还需要在中断处理文件中，添加以下中断（如果使用了其他功能的终端，自行添加）：

/**
  * @brief  OTG_FS_IRQHandler
  *          This function handles USB-On-The-Go FS global interrupt request.
  *          requests.
  * @param  None
  * @retval None
  */
#ifdef USE_USB_OTG_FS  
void OTG_FS_IRQHandler(void)
#else
void OTG_HS_IRQHandler(void)
#endif
{
    USBH_OTG_ISR_Handler(&USB_OTG_Core);
}

Fatfs部分

源码移植

目前，FatFS的最新版为R0.13a。从R0.13开始，作者将配置宏统一为可FF_开头。目前网上多数文章都是针对之前的，许多配置名与最新新版的源码是对不上。
FatfsFolder
使用FatFs最简单的只需要关系两个文件即可：ff.c/h和diskio.c/h。其中，diskio.c/h是一个模板，用户需要自行实现与底层磁盘的读写。在ST提供的USB Host驱动中，已经实现了该文件，名为usbh_msc_fatfs.c。
更进一步，在使用了其他编码例如中文及长文件名时，则需要将ffunicode.c包含到自己的项目中。此外，在使用了系统时，还必须将ffsystem.c包含到项目中，并按照自己的系统，修改该文件。

源码配置

FatFS的配置通过一个名为ffconf.h的文件实现。对于每个选项，模板中都有很详细的说明。同时，为减小FatFs占用的空间，一般只开启需要的选项。以下仅对几个特殊的进行注释性说明。

/*---------------------------------------------------------------------------/
/  FatFs - Configuration file
/---------------------------------------------------------------------------*/
#define FFCONF_DEF 89352    /* Revision ID */
/*---------------------------------------------------------------------------/
/ Function Configurations
/---------------------------------------------------------------------------*/
#define FF_FS_READONLY  0
/* This option switches read-only configuration. (0:Read/Write or 1:Read-only)
/  Read-only configuration removes writing API functions, f_write(), f_sync(),
/  f_unlink(), f_mkdir(), f_chmod(), f_rename(), f_truncate(), f_getfree()
/  and optional writing functions as well. */

#define FF_FS_MINIMIZE  0
/* This option defines minimization level to remove some basic API functions.
/
/   0: Basic functions are fully enabled.
/   1: f_stat(), f_getfree(), f_unlink(), f_mkdir(), f_truncate() and f_rename()
/      are removed.
/   2: f_opendir(), f_readdir() and f_closedir() are removed in addition to 1.
/   3: f_lseek() function is removed in addition to 2. */

#define FF_USE_STRFUNC  1
/* This option switches string functions, f_gets(), f_putc(), f_puts() and f_printf().
/
/  0: Disable string functions.
/  1: Enable without LF-CRLF conversion.
/  2: Enable with LF-CRLF conversion. */

#define FF_USE_FIND     0
/* This option switches filtered directory read functions, f_findfirst() and
/  f_findnext(). (0:Disable, 1:Enable 2:Enable with matching altname[] too) */

#define FF_USE_MKFS     0
/* This option switches f_mkfs() function. (0:Disable or 1:Enable) */

#define FF_USE_FASTSEEK 0
/* This option switches fast seek function. (0:Disable or 1:Enable) */

#define FF_USE_EXPAND   0
/* This option switches f_expand function. (0:Disable or 1:Enable) */

#define FF_USE_CHMOD    0
/* This option switches attribute manipulation functions, f_chmod() and f_utime().
/  (0:Disable or 1:Enable) Also FF_FS_READONLY needs to be 0 to enable this option. */

#define FF_USE_LABEL    0
/* This option switches volume label functions, f_getlabel() and f_setlabel().
/  (0:Disable or 1:Enable) */

#define FF_USE_FORWARD  0
/* This option switches f_forward() function. (0:Disable or 1:Enable) */
/*---------------------------------------------------------------------------/
/ Locale and Namespace Configurations
/---------------------------------------------------------------------------*/
/* Code Page，是字符编码的另一种说法。Code Page包含了一个表，表中的值，用于表示针对某种语言所用的字符集。更简单点说，就是Code Page中，用一个数字编号，表示了所要采用何种字符编码，去编解码相应的值，用于正确显示出相应的字符。*/
#define FF_CODE_PAGE    932
/* This option specifies the OEM code page to be used on the target system.
/  Incorrect code page setting can cause a file open failure.
/
/   437 - U.S.
/   720 - Arabic
/   737 - Greek
/   771 - KBL
/   775 - Baltic
/   850 - Latin 1
/   852 - Latin 2
/   855 - Cyrillic
/   857 - Turkish
/   860 - Portuguese
/   861 - Icelandic
/   862 - Hebrew
/   863 - Canadian French
/   864 - Arabic
/   865 - Nordic
/   866 - Russian
/   869 - Greek 2
/   932 - Japanese (DBCS)
/   936 - Simplified Chinese (DBCS)
/   949 - Korean (DBCS)
/   950 - Traditional Chinese (DBCS)
/     0 - Include all code pages above and configured by f_setcp()
*/
/* 长文件名。这个是微软的专利！开启后 必须包含 ffunicode.c */
#define FF_USE_LFN      0
#define FF_MAX_LFN      255
/* The FF_USE_LFN switches the support for LFN (long file name).
/
/   0: Disable LFN. FF_MAX_LFN has no effect.
/   1: Enable LFN with static working buffer on the BSS. Always NOT thread-safe.
/   2: Enable LFN with dynamic working buffer on the STACK.
/   3: Enable LFN with dynamic working buffer on the HEAP.
/
/  To enable the LFN, ffunicode.c needs to be added to the project. The LFN function
/  requiers certain internal working buffer occupies (FF_MAX_LFN + 1) * 2 bytes and
/  additional (FF_MAX_LFN + 44) / 15 * 32 bytes when exFAT is enabled.
/  The FF_MAX_LFN defines size of the working buffer in UTF-16 code unit and it can
/  be in range of 12 to 255. It is recommended to be set 255 to fully support LFN
/  specification.
/  When use stack for the working buffer, take care on stack overflow. When use heap
/  memory for the working buffer, memory management functions, ff_memalloc() and
/  ff_memfree() in ffsystem.c, need to be added to the project. */
/* 必须开启 Unicode支持 */
#define FF_LFN_UNICODE  0
/* This option switches the character encoding on the API when LFN is enabled.
/
/   0: ANSI/OEM in current CP (TCHAR = char)
/   1: Unicode in UTF-16 (TCHAR = WCHAR)
/   2: Unicode in UTF-8 (TCHAR = char)
/
/  Also behavior of string I/O functions will be affected by this option.
/  When LFN is not enabled, this option has no effect. */

#define FF_LFN_BUF      255
#define FF_SFN_BUF      12
/* This set of options defines size of file name members in the FILINFO structure
/  which is used to read out directory items. These values should be suffcient for
/  the file names to read. The maximum possible length of the read file name depends
/  on character encoding. When LFN is not enabled, these options have no effect. */

#define FF_STRF_ENCODE  3
/* When FF_LFN_UNICODE >= 1 with LFN enabled, string I/O functions, f_gets(),
/  f_putc(), f_puts and f_printf() convert the character encoding in it.
/  This option selects assumption of character encoding ON THE FILE to be
/  read/written via those functions.
/
/   0: ANSI/OEM in current CP
/   1: Unicode in UTF-16LE
/   2: Unicode in UTF-16BE
/   3: Unicode in UTF-8
*/

#define FF_FS_RPATH     0
/* This option configures support for relative path.
/
/   0: Disable relative path and remove related functions.
/   1: Enable relative path. f_chdir() and f_chdrive() are available.
/   2: f_getcwd() function is available in addition to 1.
*/
/*---------------------------------------------------------------------------/
/ Drive/Volume Configurations
/---------------------------------------------------------------------------*/
#define FF_VOLUMES      1
/* Number of volumes (logical drives) to be used. (1-10) */

#define FF_STR_VOLUME_ID    0
#define FF_VOLUME_STRS      "RAM","NAND","CF","SD","SD2","USB","USB2","USB3"
/* FF_STR_VOLUME_ID switches string support for volume ID.
/  When FF_STR_VOLUME_ID is set to 1, also pre-defined strings can be used as drive
/  number in the path name. FF_VOLUME_STRS defines the drive ID strings for each
/  logical drives. Number of items must be equal to FF_VOLUMES. Valid characters for
/  the drive ID strings are: A-Z and 0-9. */

#define FF_MULTI_PARTITION  0
/* This option switches support for multiple volumes on the physical drive.
/  By default (0), each logical drive number is bound to the same physical drive
/  number and only an FAT volume found on the physical drive will be mounted.
/  When this function is enabled (1), each logical drive number can be bound to
/  arbitrary physical drive and partition listed in the VolToPart[]. Also f_fdisk()
/  funciton will be available. */

#define FF_MIN_SS       512
#define FF_MAX_SS       512
/* This set of options configures the range of sector size to be supported. (512,
/  1024, 2048 or 4096) Always set both 512 for most systems, generic memory card and
/  harddisk. But a larger value may be required for on-board flash memory and some
/  type of optical media. When FF_MAX_SS is larger than FF_MIN_SS, FatFs is configured
/  for variable sector size mode and disk_ioctl() function needs to implement
/  GET_SECTOR_SIZE command. */

#define FF_USE_TRIM     0
/* This option switches support for ATA-TRIM. (0:Disable or 1:Enable)
/  To enable Trim function, also CTRL_TRIM command should be implemented to the
/  disk_ioctl() function. */

#define FF_FS_NOFSINFO  0
/* If you need to know correct free space on the FAT32 volume, set bit 0 of this
/  option, and f_getfree() function at first time after volume mount will force
/  a full FAT scan. Bit 1 controls the use of last allocated cluster number.
/
/  bit0=0: Use free cluster count in the FSINFO if available.
/  bit0=1: Do not trust free cluster count in the FSINFO.
/  bit1=0: Use last allocated cluster number in the FSINFO if available.
/  bit1=1: Do not trust last allocated cluster number in the FSINFO.
*/

/*---------------------------------------------------------------------------/
/ System Configurations
/---------------------------------------------------------------------------*/
#define FF_FS_TINY      0
/* This option switches tiny buffer configuration. (0:Normal or 1:Tiny)
/  At the tiny configuration, size of file object (FIL) is shrinked FF_MAX_SS bytes.
/  Instead of private sector buffer eliminated from the file object, common sector
/  buffer in the filesystem object (FATFS) is used for the file data transfer. */

#define FF_FS_EXFAT     0
/* This option switches support for exFAT filesystem. (0:Disable or 1:Enable)
/  When enable exFAT, also LFN needs to be enabled.
/  Note that enabling exFAT discards ANSI C (C89) compatibility. */

#define FF_FS_NORTC     0
#define FF_NORTC_MON    1
#define FF_NORTC_MDAY   1
#define FF_NORTC_YEAR   2017
/* The option FF_FS_NORTC switches timestamp functiton. If the system does not have
/  any RTC function or valid timestamp is not needed, set FF_FS_NORTC = 1 to disable
/  the timestamp function. All objects modified by FatFs will have a fixed timestamp
/  defined by FF_NORTC_MON, FF_NORTC_MDAY and FF_NORTC_YEAR in local time.
/  To enable timestamp function (FF_FS_NORTC = 0), get_fattime() function need to be
/  added to the project to read current time form real-time clock. FF_NORTC_MON,
/  FF_NORTC_MDAY and FF_NORTC_YEAR have no effect.
/  These options have no effect at read-only configuration (FF_FS_READONLY = 1). */

#define FF_FS_LOCK      0
/* The option FF_FS_LOCK switches file lock function to control duplicated file open
/  and illegal operation to open objects. This option must be 0 when FF_FS_READONLY
/  is 1.
/
/  0:  Disable file lock function. To avoid volume corruption, application program
/      should avoid illegal open, remove and rename to the open objects.
/  >0: Enable file lock function. The value defines how many files/sub-directories
/      can be opened simultaneously under file lock control. Note that the file
/      lock control is independent of re-entrancy. */
#define FF_FS_REENTRANT 0
#define FF_FS_TIMEOUT   1000
#define FF_SYNC_t       HANDLE
/* The option FF_FS_REENTRANT switches the re-entrancy (thread safe) of the FatFs
/  module itself. Note that regardless of this option, file access to different
/  volume is always re-entrant and volume control functions, f_mount(), f_mkfs()
/  and f_fdisk() function, are always not re-entrant. Only file/directory access
/  to the same volume is under control of this function.
/
/   0: Disable re-entrancy. FF_FS_TIMEOUT and FF_SYNC_t have no effect.
/   1: Enable re-entrancy. Also user provided synchronization handlers,
/      ff_req_grant(), ff_rel_grant(), ff_del_syncobj() and ff_cre_syncobj()
/      function, must be added to the project. Samples are available in
/      option/syscall.c.
/
/  The FF_FS_TIMEOUT defines timeout period in unit of time tick.
/  The FF_SYNC_t defines O/S dependent sync object type. e.g. HANDLE, ID, OS_EVENT*,
/  SemaphoreHandle_t and etc. A header file for O/S definitions needs to be
/  included somewhere in the scope of ff.h. */
/* #include <windows.h> // O/S definitions  */
/*--- End of configuration options ---*/

注意事项

FatFs从R0.13开始，源码结构与之间变化不少，变得更简洁。需要使用者修改了diskio.c和ffsystem.也给出了模板，只需要做对应修改即可。
关于字符编码(Code Page)参考字符编码详解。字符编码选择错误可能导致读写文件失败！！！
长文件名是微软的专利，使用时需要注意！长文件名使用Unicode编码，因此必须包含ffunicode.c。在该文件中，FatFs的作者给出了对应文件编码的转换表和对应的转换函数ff_convert()和 ff_wtoupper()。

参考文档

STM32F105xx, STM32F107xx, STM32F2xx and STM32F4xx USB On-The-Go host and device library User manual
Universal Serial Bus Revision 2.0 specification
USB 2.0 On-The-Go Specification Supplement Adopters Agreement
Fatfs 官方文档 http://elm-chan.org/fsw/ff/00index_e.html