STM32 USB学习笔记4
2016-02-25 11:35
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主机环境：Windows 7 SP1
开发环境：MDK5.14
目标板：STM32F103C8T6
开发库：STM32F1Cube库和STM32_USB_Device_Library
前面分析了USB的描述符文件，现在分析一下usbd_conf文件，usbd_conf.h文件是配置文件，如下：
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __USBD_CONF_H
#define __USBD_CONF_H
/* Includes ------------------------------------------------------------------*/
#include "stm32f1xx_hal.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Exported types ------------------------------------------------------------*/
/* Exported constants --------------------------------------------------------*/
/* Common Config */
#define USBD_MAX_NUM_INTERFACES 1
#define USBD_MAX_NUM_CONFIGURATION 1
#define USBD_MAX_STR_DESC_SIZ 0x100
#define USBD_SUPPORT_USER_STRING 0
#define USBD_SELF_POWERED 1
#define USBD_DEBUG_LEVEL 0
/* Exported macro ------------------------------------------------------------*/
/* Memory management macros */
/* For footprint reasons and since only one allocation is handled in the CDC class
driver, the malloc/free is changed into a static allocation method */
void *USBD_static_malloc(uint32_t size);
void USBD_static_free(void *p);
#define MAX_STATIC_ALLOC_SIZE 140 /* CDC Class Driver Structure size */
#define USBD_malloc (uint32_t *)USBD_static_malloc
#define USBD_free USBD_static_free
#define USBD_memset /* Not used */
#define USBD_memcpy /* Not used */
/* DEBUG macros */
#if (USBD_DEBUG_LEVEL > 0)
#define USBD_UsrLog(...) printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_UsrLog(...)
#endif
#if (USBD_DEBUG_LEVEL > 1)
#define USBD_ErrLog(...) printf("ERROR: ") ;\
printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_ErrLog(...)
#endif
#if (USBD_DEBUG_LEVEL > 2)
#define USBD_DbgLog(...) printf("DEBUG : ") ;\
printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_DbgLog(...)
#endif
/* Exported functions ------------------------------------------------------- */
#endif /* __USBD_CONF_H */配置文件很简单，指明最大接口数为1，最大配置数为1，不支持用户字符串，支持自供电，调试级别为0，在USB通信中USB设备支持两种供电方式：自供电(设备有自己独立电源)，总线供电(设备由USB主机提供电源)。同时，在这里采用静态空间分配方案，分配的静态空间大小为140字节。调试界别为0是没有调试信息输出的，根据自己需求来使能调试功能。usbd_conf.c文件要复杂一些，用于实现USB设备库的回调函数以及MCU的一些底层初始化。各个中断的服务例程在stm32f1xx_it.c文件中，如下：
void SysTick_Handler(void)
{
Toggle_Leds();
HAL_IncTick();
}
/******************************************************************************/
/* STM32F1xx Peripherals Interrupt Handlers */
/* Add here the Interrupt Handler for the used peripheral(s) (PPP), for the */
/* available peripheral interrupt handler's name please refer to the startup */
/* file (startup_stm32f1xx.s). */
/******************************************************************************/
/**
* @brief This function handles USB Handler.
* @param None
* @retval None
*/
void USB_LP_CAN1_RX0_IRQHandler(void)
{
HAL_PCD_IRQHandler(&hpcd);
}
/**
* @brief This function handles DMA interrupt request.
* @param None
* @retval None
*/
void USARTx_DMA_TX_IRQHandler(void)
{
HAL_DMA_IRQHandler(UartHandle.hdmatx);
}
/**
* @brief This function handles UART interrupt request.
* @param None
* @retval None
*/
void USARTx_IRQHandler(void)
{
HAL_UART_IRQHandler(&UartHandle);
}
/**
* @brief This function handles TIM interrupt request.
* @param None
* @retval None
*/
void TIMx_IRQHandler(void)
{
HAL_TIM_IRQHandler(&TimHandle);
}中断服务例程很简单提供了一个IRQHandler接口，通过该接口会调用一些回调函数来实现具体的处理，其中各个接口可以在库函数说明中找到，如下：
USB底层API如下：
以上这些接口是需要在usbd_conf.c文件中实现的，此外还有一个USB接口的硬件IO初始化，如下：
/**
* @brief Initializes the PCD MSP.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_MspInit(PCD_HandleTypeDef *hpcd)
{
GPIO_InitTypeDef GPIO_InitStruct;
/* Enable the GPIOA clock */
__HAL_RCC_GPIOA_CLK_ENABLE();
/* Configure USB DM/DP pins */
GPIO_InitStruct.Pin = (GPIO_PIN_11 | GPIO_PIN_12);
GPIO_InitStruct.Mode = GPIO_MODE_AF_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* Enable USB Clock */
__HAL_RCC_USB_CLK_ENABLE();
/* Set USB Interrupt priority */
HAL_NVIC_SetPriority(USB_LP_CAN1_RX0_IRQn, 7, 0);
/* Enable USB Interrupt */
HAL_NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
}
/**
* @brief De-Initializes the PCD MSP.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_MspDeInit(PCD_HandleTypeDef *hpcd)
{
/* Disable USB FS Clock */
__HAL_RCC_USB_CLK_DISABLE();
}
设置USB的硬件IO口为复用模式，并设置中断优先级且使能USB中断，USB中断号有三个：USB低优先级中断(20)，USB高优先级中断(19)，USB唤醒中断(42)，这里是使能的USB低优先级中断，所有的USB事件均可触发该中断。USB底层回调函数接口实现如下：
/*******************************************************************************
LL Driver Callbacks (PCD -> USB Device Library)
*******************************************************************************/
/**
* @brief SetupStage callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SetupStageCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SetupStage((USBD_HandleTypeDef*)hpcd->pData, (uint8_t *)hpcd->Setup);
}
/**
* @brief DataOut Stage callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_DataOutStageCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_DataOutStage((USBD_HandleTypeDef*)hpcd->pData, epnum, hpcd->OUT_ep[epnum].xfer_buff);
}
/**
* @brief DataIn Stage callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_DataInStageCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_DataInStage((USBD_HandleTypeDef*)hpcd->pData, epnum, hpcd->IN_ep[epnum].xfer_buff);
}
/**
* @brief SOF callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SOFCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SOF((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Reset callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ResetCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SetSpeed((USBD_HandleTypeDef*)hpcd->pData, USBD_SPEED_FULL);
/* Reset Device */
USBD_LL_Reset((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Suspend callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SuspendCallback(PCD_HandleTypeDef *hpcd)
{
/* Inform USB library that core enters in suspend Mode */
USBD_LL_Suspend((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Resume callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ResumeCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_Resume((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief ISOOUTIncomplete callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_ISOOUTIncompleteCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_IsoOUTIncomplete((USBD_HandleTypeDef*)hpcd->pData, epnum);
}
/**
* @brief ISOINIncomplete callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_ISOINIncompleteCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_IsoINIncomplete((USBD_HandleTypeDef*)hpcd->pData, epnum);
}
/**
* @brief ConnectCallback callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ConnectCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_DevConnected((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Disconnect callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_DisconnectCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_DevDisconnected((USBD_HandleTypeDef*)hpcd->pData);
}每一个回调函数都是调用的usbd_core.c中的底层函数，对于不同的USB类该回调函数的接口实现是类似的，分别对应了触发USB中断的各个情况，跟串口中断不同，串口中断我们一般关心接收和发送中断即可。而USB的中断源比较多，从回调函数的个数就可以看得出来，即使这样，但这些回调函数里面有几个是为空的，如同步传输完成的回调函数以及设备连接的回调函数，此外，HAL_PCD_IRQHandler()里是没有调用同步传输完成回调函数的，在OTG模块的中断服务例程里才有调用。既然在全速模式下回调函数为空就不必刻意关注该回调函数了。重点关注Setup、DataIn、DataOut等即可，与之相关的是USB通信中的Setup阶段、数据阶段，所有的USB通信请求都是由USB主机发起，一般分为三个阶段：设置阶段、数据阶段、状态阶段。其中数据阶段是可以省略的。具体内容在后面遇到再分析，至此，USB中断底层回调函数浏览完毕，还剩下底层的设备驱动API，在分析之前需要注意两个个重要的结构体PCD_HandleTypeDef和USBD_HandleTypeDef，前者是STM32Cube库提供的跟寄存器相关的数据结构，后者是USB器件库提供的跟USB协议相关的数据结构，在例程中两者相互引用，PCD_HandleTypeDef结构如下：
/**
* @brief PCD Handle Structure definition
*/
typedef struct
{
PCD_TypeDef *Instance; /*!< Register base address */
PCD_InitTypeDef Init; /*!< PCD required parameters */
__IO uint8_t USB_Address; /*!< USB Address: not used by USB OTG FS */
PCD_EPTypeDef IN_ep[15]; /*!< IN endpoint parameters */
PCD_EPTypeDef OUT_ep[15]; /*!< OUT endpoint parameters */
HAL_LockTypeDef Lock; /*!< PCD peripheral status */
__IO PCD_StateTypeDef State; /*!< PCD communication state */
uint32_t Setup[12]; /*!< Setup packet buffer */
void *pData; /*!< Pointer to upper stack Handler */
} PCD_HandleTypeDef;
/**
* @brief PCD State structure definition
*/
typedef enum
{
HAL_PCD_STATE_RESET = 0x00,
HAL_PCD_STATE_READY = 0x01,
HAL_PCD_STATE_ERROR = 0x02,
HAL_PCD_STATE_BUSY = 0x03,
HAL_PCD_STATE_TIMEOUT = 0x04
} PCD_StateTypeDef;
#if defined (USB)
typedef USB_TypeDef PCD_TypeDef;
typedef USB_CfgTypeDef PCD_InitTypeDef;
typedef USB_EPTypeDef PCD_EPTypeDef;
#endif /* USB */
/**
* @brief Universal Serial Bus Full Speed Device
*/
typedef struct
{
__IO uint16_t EP0R; /*!< USB Endpoint 0 register, Address offset: 0x00 */
__IO uint16_t RESERVED0; /*!< Reserved */
__IO uint16_t EP1R; /*!< USB Endpoint 1 register, Address offset: 0x04 */
__IO uint16_t RESERVED1; /*!< Reserved */
__IO uint16_t EP2R; /*!< USB Endpoint 2 register, Address offset: 0x08 */
__IO uint16_t RESERVED2; /*!< Reserved */
__IO uint16_t EP3R; /*!< USB Endpoint 3 register, Address offset: 0x0C */
__IO uint16_t RESERVED3; /*!< Reserved */
__IO uint16_t EP4R; /*!< USB Endpoint 4 register, Address offset: 0x10 */
__IO uint16_t RESERVED4; /*!< Reserved */
__IO uint16_t EP5R; /*!< USB Endpoint 5 register, Address offset: 0x14 */
__IO uint16_t RESERVED5; /*!< Reserved */
__IO uint16_t EP6R; /*!< USB Endpoint 6 register, Address offset: 0x18 */
__IO uint16_t RESERVED6; /*!< Reserved */
__IO uint16_t EP7R; /*!< USB Endpoint 7 register, Address offset: 0x1C */
__IO uint16_t RESERVED7[17]; /*!< Reserved */
__IO uint16_t CNTR; /*!< Control register, Address offset: 0x40 */
__IO uint16_t RESERVED8; /*!< Reserved */
__IO uint16_t ISTR; /*!< Interrupt status register, Address offset: 0x44 */
__IO uint16_t RESERVED9; /*!< Reserved */
__IO uint16_t FNR; /*!< Frame number register, Address offset: 0x48 */
__IO uint16_t RESERVEDA; /*!< Reserved */
__IO uint16_t DADDR; /*!< Device address register, Address offset: 0x4C */
__IO uint16_t RESERVEDB; /*!< Reserved */
__IO uint16_t BTABLE; /*!< Buffer Table address register, Address offset: 0x50 */
__IO uint16_t RESERVEDC; /*!< Reserved */
} USB_TypeDef;
#if defined (USB)
/**
* @brief USB Initialization Structure definition
*/
typedef struct
{
uint32_t dev_endpoints; /*!< Device Endpoints number.
This parameter depends on the used USB core.
This parameter must be a number between Min_Data = 1 and Max_Data = 15 */
uint32_t speed; /*!< USB Core speed.
This parameter can be any value of @ref USB_Core_Speed */
uint32_t ep0_mps; /*!< Set the Endpoint 0 Max Packet size.
This parameter can be any value of @ref USB_EP0_MPS */
uint32_t phy_itface; /*!< Select the used PHY interface.
This parameter can be any value of @ref USB_Core_PHY */
uint32_t Sof_enable; /*!< Enable or disable the output of the SOF signal. */
uint32_t low_power_enable; /*!< Enable or disable Low Power mode */
uint32_t lpm_enable; /*!< Enable or disable Battery charging. */
uint32_t battery_charging_enable; /*!< Enable or disable Battery charging. */
} USB_CfgTypeDef;
typedef struct
{
uint8_t num; /*!< Endpoint number
This parameter must be a number between Min_Data = 1 and Max_Data = 15 */
uint8_t is_in; /*!< Endpoint direction
This parameter must be a number between Min_Data = 0 and Max_Data = 1 */
uint8_t is_stall; /*!< Endpoint stall condition
This parameter must be a number between Min_Data = 0 and Max_Data = 1 */
uint8_t type; /*!< Endpoint type
This parameter can be any value of @ref USB_EP_Type */
uint16_t pmaadress; /*!< PMA Address
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint16_t pmaaddr0; /*!< PMA Address0
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint16_t pmaaddr1; /*!< PMA Address1
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint8_t doublebuffer; /*!< Double buffer enable
This parameter can be 0 or 1 */
uint16_t tx_fifo_num; /*!< This parameter is not required by USB Device FS peripheral, it is used
only by USB OTG FS peripheral
This parameter is added to ensure compatibility across USB peripherals */
uint32_t maxpacket; /*!< Endpoint Max packet size
This parameter must be a number between Min_Data = 0 and Max_Data = 64KB */
uint8_t *xfer_buff; /*!< Pointer to transfer buffer */
uint32_t xfer_len; /*!< Current transfer length */
uint32_t xfer_count; /*!< Partial transfer length in case of multi packet transfer */
} USB_EPTypeDef;
#endif /* USB */其中USB_TypeDef结构跟STM32寄存器相关，可通过查看STM32F103C8T6参考手册来熟悉USB相关寄存器。剩余的两个结构USB_CfgTypeDef和USB_EPTypeDef跟STM32中USB模块的特性相关，因此需要多多熟悉相对应的参考手册，STM32F103C8T6可提供16个单向端点，至于PCD_HandleTypeDef中Setup数组大小为12，还不清楚为什么是12，USB协议中Setup包大小是8个字节，而这里是48个字节，后面有眉目了再说吧。对于USB器件库的使用来说PCD_HandleTypeDef结构体没有USBD_HandleTypeDef结构体重要，USBD_HandleTypeDef结构体是USB器件库中核心结构体，如下：
/* USB Device handle structure */
typedef struct _USBD_HandleTypeDef
{
uint8_t id;
uint32_t dev_config;
uint32_t dev_default_config;
uint32_t dev_config_status;
USBD_SpeedTypeDef dev_speed;
USBD_EndpointTypeDef ep_in[15];
USBD_EndpointTypeDef ep_out[15];
uint32_t ep0_state;
uint32_t ep0_data_len;
uint8_t dev_state;
uint8_t dev_old_state;
uint8_t dev_address;
uint8_t dev_connection_status;
uint8_t dev_test_mode;
uint32_t dev_remote_wakeup;
USBD_SetupReqTypedef request;
USBD_DescriptorsTypeDef *pDesc;
USBD_ClassTypeDef *pClass;
void *pClassData;
void *pUserData;
void *pData;
} USBD_HandleTypeDef;
/* Following USB Device Speed */
typedef enum
{
USBD_SPEED_HIGH = 0,
USBD_SPEED_FULL = 1,
USBD_SPEED_LOW = 2,
}USBD_SpeedTypeDef;
/* USB Device handle structure */
typedef struct
{
uint32_t status;
uint32_t total_length;
uint32_t rem_length;
uint32_t maxpacket;
} USBD_EndpointTypeDef;
/** @defgroup USBD_DEF_Exported_TypesDefinitions
* @{
*/
typedef struct usb_setup_req
{
uint8_t bmRequest;
uint8_t bRequest;
uint16_t wValue;
uint16_t wIndex;
uint16_t wLength;
}USBD_SetupReqTypedef;
typedef struct _Device_cb
{
uint8_t (*Init) (struct _USBD_HandleTypeDef *pdev , uint8_t cfgidx);
uint8_t (*DeInit) (struct _USBD_HandleTypeDef *pdev , uint8_t cfgidx);
/* Control Endpoints*/
uint8_t (*Setup) (struct _USBD_HandleTypeDef *pdev , USBD_SetupReqTypedef *req);
uint8_t (*EP0_TxSent) (struct _USBD_HandleTypeDef *pdev );
uint8_t (*EP0_RxReady) (struct _USBD_HandleTypeDef *pdev );
/* Class Specific Endpoints*/
uint8_t (*DataIn) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*DataOut) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*SOF) (struct _USBD_HandleTypeDef *pdev);
uint8_t (*IsoINIncomplete) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*IsoOUTIncomplete) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t *(*GetHSConfigDescriptor)(uint16_t *length);
uint8_t *(*GetFSConfigDescriptor)(uint16_t *length);
uint8_t *(*GetOtherSpeedConfigDescriptor)(uint16_t *length);
uint8_t *(*GetDeviceQualifierDescriptor)(uint16_t *length);
#if (USBD_SUPPORT_USER_STRING == 1)
uint8_t *(*GetUsrStrDescriptor)(struct _USBD_HandleTypeDef *pdev ,uint8_t index, uint16_t *length);
#endif
} USBD_ClassTypeDef;一个USB总线最多可支持1128个设备，地址范围为0~127，因此这里用一个字节的dev_address来存储唯一的设备地址。而USBD_SetupReqTypedef结构体跟USB协议相关，USB协议中定义的Setup请求格式如下：
可以看到二者相匹配，获取setup请求更多详情，请参考USB2.0协议规范中第九章节。同时可以看到在USBD_HandleTypeDef结构体中包含了之前提到的描述符结构体USBD_DescriptorTypeDef，此外还包含了一个新的结构体设备类结构体USBD_ClassTypeDef，它里面是各个回调函数，在USB中断的回调函数中会调用设备类中的回调函数来实现具体功能，USB器件库手册中说明了设备类回调函数的作用，如下：
这些接口的实现是在CDC接口文件中实现，后面再分析，PCD_HandleTypeDef和USBD_HandleTypeDef结构通过void指针相互引用。
USB模块中静态空间分配方案实现如下：
/**
* @brief static single allocation.
* @param size: size of allocated memory
* @retval None
*/
void *USBD_static_malloc(uint32_t size)
{
static uint32_t mem[MAX_STATIC_ALLOC_SIZE];
return mem;
}
/**
* @brief Dummy memory free
* @param *p pointer to allocated memory address
* @retval None
*/
void USBD_static_free(void *p)
{
}实现很简单申请一块静态空间并返回给调用者。USB设备驱动的底层API实现如下：
/*******************************************************************************
LL Driver Interface (USB Device Library --> PCD)
*******************************************************************************/
/**
* @brief Initializes the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Init(USBD_HandleTypeDef *pdev)
{
/* Set LL Driver parameters */
hpcd.Instance = USB;
hpcd.Init.dev_endpoints = 8; //STM32F103C8T6Ö§³Ö8¸öË«Ïò¶Ëµã
hpcd.Init.ep0_mps = PCD_EP0MPS_64; //¶Ëµã0Ö§³ÖµÄ×î´ó·Ö×é×Ö½ÚΪ64
hpcd.Init.phy_itface = PCD_PHY_EMBEDDED;
hpcd.Init.speed = PCD_SPEED_FULL; //USB2.0È«ËÙÉ豸
hpcd.Init.low_power_enable = 0; //²»Ê¹Äܵ͹¦ºÄģʽ
/* Link The driver to the stack */
hpcd.pData = pdev;
pdev->pData = &hpcd;
/* Initialize LL Driver */
HAL_PCD_Init((PCD_HandleTypeDef*)pdev->pData);
HAL_PCDEx_PMAConfig(pdev->pData , 0x00 , PCD_SNG_BUF, 0x40); //OUT¶Ëµã
HAL_PCDEx_PMAConfig(pdev->pData , 0x80 , PCD_SNG_BUF, 0x80); //IN¶Ëµã
HAL_PCDEx_PMAConfig(pdev->pData , CDC_IN_EP , PCD_SNG_BUF, 0xC0);
HAL_PCDEx_PMAConfig(pdev->pData , CDC_OUT_EP , PCD_SNG_BUF, 0x110);
HAL_PCDEx_PMAConfig(pdev->pData , CDC_CMD_EP , PCD_SNG_BUF, 0x100);
return USBD_OK;
}
/**
* @brief De-Initializes the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_DeInit(USBD_HandleTypeDef *pdev)
{
HAL_PCD_DeInit((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Starts the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Start(USBD_HandleTypeDef *pdev)
{
HAL_PCD_Start((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Stops the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Stop(USBD_HandleTypeDef *pdev)
{
HAL_PCD_Stop((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Opens an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param ep_type: Endpoint Type
* @param ep_mps: Endpoint Max Packet Size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_OpenEP(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t ep_type,
uint16_t ep_mps)
{
HAL_PCD_EP_Open((PCD_HandleTypeDef*)pdev->pData,
ep_addr,
ep_mps,
ep_type);
return USBD_OK;
}
/**
* @brief Closes an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_CloseEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_Close((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Flushes an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_FlushEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_Flush((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Sets a Stall condition on an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_StallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_SetStall((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Clears a Stall condition on an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_ClearStallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_ClrStall((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Returns Stall condition.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval Stall (1: Yes, 0: No)
*/
uint8_t USBD_LL_IsStallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
PCD_HandleTypeDef *hpcd = (PCD_HandleTypeDef*)pdev->pData;
if ((ep_addr & 0x80) == 0x80)
{
return hpcd->IN_ep[ep_addr & 0x7F].is_stall;
}
else
{
return hpcd->OUT_ep[ep_addr & 0x7F].is_stall;
}
}
/**
* @brief Assigns a USB address to the device.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_SetUSBAddress(USBD_HandleTypeDef *pdev, uint8_t dev_addr)
{
HAL_PCD_SetAddress((PCD_HandleTypeDef*)pdev->pData, dev_addr);
return USBD_OK;
}
/**
* @brief Transmits data over an endpoint.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param pbuf: Pointer to data to be sent
* @param size: Data size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Transmit(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint16_t size)
{
HAL_PCD_EP_Transmit((PCD_HandleTypeDef*)pdev->pData, ep_addr, pbuf, size);
return USBD_OK;
}
/**
* @brief Prepares an endpoint for reception.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param pbuf: Pointer to data to be received
* @param size: Data size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_PrepareReceive(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint16_t size)
{
HAL_PCD_EP_Receive((PCD_HandleTypeDef*)pdev->pData, ep_addr, pbuf, size);
return USBD_OK;
}
/**
* @brief Returns the last transferred packet size.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval Recived Data Size
*/
uint32_t USBD_LL_GetRxDataSize(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
return HAL_PCD_EP_GetRxCount((PCD_HandleTypeDef*)pdev->pData, ep_addr);
}
/**
* @brief Delays routine for the USB Device Library.
* @param Delay: Delay in ms
* @retval None
*/
void USBD_LL_Delay(uint32_t Delay)
{
HAL_Delay(Delay);
}这些底层驱动的实现大部分都是调用Cube库中USB接口，其具体实现不必刻意关注，如果有空闲可以静心研究其寄存器的操作，我们一般只关心底层接口即可，比较复杂的一个接口是USBD_LL_Init()，USB中端点分为IN端点和OUT端点，共16个端点，在USB器件库中使用一个字节来表示，最高位为0是OUT端点，最高位为1是IN端点，USBD_LL_Init()中设置端点数为8，端点0最大包大小为64字节，为全速设备，不支持低功耗模式，并通过void指针pData来实现USBD_HandleTypeDef和PCD_HandleTypeDef结构的相互引用，HAL_PCDEx_PMAConfig()函数来设置端点缓冲区大小，这里使用了5个单向端点，有关分组缓冲的的描述可以在对应的参考手册上查找到，示例如下：
STM32中有单独的512个字节是作为USB分组缓冲区，该区域的地址为0x4000_6000~0x4000_63FF，USB和CAN模块共用该区域，因此二者不能同时访问，可以互斥访问，有关分组缓冲区有两类寄存器：USB分组缓冲区描述表地址寄存器(USB_BTABLE
);缓冲区描述表寄存器。如上图所示缓冲区描述表寄存器是几组寄存器的集合(一共8个端点共8组集合，每组里包含了4个寄存器：ADDRn_TX、COUNTn_TX、ADDRn_RX、COUNTn_RX)。这些寄存器的地址是可变的，在0x4000_6000~0x4000_63FF中，具体地址由USB_BTABLE寄存器指定，在本例中USB_BTABLE指定为0，如下：
#define BTABLE_ADDRESS (0x000)
/*Set Btable Address*/
USBx->BTABLE = BTABLE_ADDRESS;对于每个端点的缓冲区地址及大小则由缓冲区描述表中的对应的4个寄存器来指定。分组缓冲区的访问是32bit的，所以虽然0x4000_0000~0x4000_63FF(共1K字节)，但实际上只用了512字节。此外，这也是为何USB有两种地址表示方式，一个是USB本地地址，另一个是应用程序访问USB分组缓冲地址。在示例中设置默认的控制端点的分组大小为64字节，这也和端点0的最大包大小为64相符，且都是使用的单缓冲端点，至此，usbd_conf文件分析完毕。
开发环境：MDK5.14
目标板：STM32F103C8T6
开发库：STM32F1Cube库和STM32_USB_Device_Library
前面分析了USB的描述符文件，现在分析一下usbd_conf文件，usbd_conf.h文件是配置文件，如下：
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __USBD_CONF_H
#define __USBD_CONF_H
/* Includes ------------------------------------------------------------------*/
#include "stm32f1xx_hal.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Exported types ------------------------------------------------------------*/
/* Exported constants --------------------------------------------------------*/
/* Common Config */
#define USBD_MAX_NUM_INTERFACES 1
#define USBD_MAX_NUM_CONFIGURATION 1
#define USBD_MAX_STR_DESC_SIZ 0x100
#define USBD_SUPPORT_USER_STRING 0
#define USBD_SELF_POWERED 1
#define USBD_DEBUG_LEVEL 0
/* Exported macro ------------------------------------------------------------*/
/* Memory management macros */
/* For footprint reasons and since only one allocation is handled in the CDC class
driver, the malloc/free is changed into a static allocation method */
void *USBD_static_malloc(uint32_t size);
void USBD_static_free(void *p);
#define MAX_STATIC_ALLOC_SIZE 140 /* CDC Class Driver Structure size */
#define USBD_malloc (uint32_t *)USBD_static_malloc
#define USBD_free USBD_static_free
#define USBD_memset /* Not used */
#define USBD_memcpy /* Not used */
/* DEBUG macros */
#if (USBD_DEBUG_LEVEL > 0)
#define USBD_UsrLog(...) printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_UsrLog(...)
#endif
#if (USBD_DEBUG_LEVEL > 1)
#define USBD_ErrLog(...) printf("ERROR: ") ;\
printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_ErrLog(...)
#endif
#if (USBD_DEBUG_LEVEL > 2)
#define USBD_DbgLog(...) printf("DEBUG : ") ;\
printf(__VA_ARGS__);\
printf("\n");
#else
#define USBD_DbgLog(...)
#endif
/* Exported functions ------------------------------------------------------- */
#endif /* __USBD_CONF_H */配置文件很简单，指明最大接口数为1，最大配置数为1，不支持用户字符串，支持自供电，调试级别为0，在USB通信中USB设备支持两种供电方式：自供电(设备有自己独立电源)，总线供电(设备由USB主机提供电源)。同时，在这里采用静态空间分配方案，分配的静态空间大小为140字节。调试界别为0是没有调试信息输出的，根据自己需求来使能调试功能。usbd_conf.c文件要复杂一些，用于实现USB设备库的回调函数以及MCU的一些底层初始化。各个中断的服务例程在stm32f1xx_it.c文件中，如下：
void SysTick_Handler(void)
{
Toggle_Leds();
HAL_IncTick();
}
/******************************************************************************/
/* STM32F1xx Peripherals Interrupt Handlers */
/* Add here the Interrupt Handler for the used peripheral(s) (PPP), for the */
/* available peripheral interrupt handler's name please refer to the startup */
/* file (startup_stm32f1xx.s). */
/******************************************************************************/
/**
* @brief This function handles USB Handler.
* @param None
* @retval None
*/
void USB_LP_CAN1_RX0_IRQHandler(void)
{
HAL_PCD_IRQHandler(&hpcd);
}
/**
* @brief This function handles DMA interrupt request.
* @param None
* @retval None
*/
void USARTx_DMA_TX_IRQHandler(void)
{
HAL_DMA_IRQHandler(UartHandle.hdmatx);
}
/**
* @brief This function handles UART interrupt request.
* @param None
* @retval None
*/
void USARTx_IRQHandler(void)
{
HAL_UART_IRQHandler(&UartHandle);
}
/**
* @brief This function handles TIM interrupt request.
* @param None
* @retval None
*/
void TIMx_IRQHandler(void)
{
HAL_TIM_IRQHandler(&TimHandle);
}中断服务例程很简单提供了一个IRQHandler接口，通过该接口会调用一些回调函数来实现具体的处理，其中各个接口可以在库函数说明中找到，如下：
USB底层API如下：
以上这些接口是需要在usbd_conf.c文件中实现的，此外还有一个USB接口的硬件IO初始化，如下：
/**
* @brief Initializes the PCD MSP.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_MspInit(PCD_HandleTypeDef *hpcd)
{
GPIO_InitTypeDef GPIO_InitStruct;
/* Enable the GPIOA clock */
__HAL_RCC_GPIOA_CLK_ENABLE();
/* Configure USB DM/DP pins */
GPIO_InitStruct.Pin = (GPIO_PIN_11 | GPIO_PIN_12);
GPIO_InitStruct.Mode = GPIO_MODE_AF_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* Enable USB Clock */
__HAL_RCC_USB_CLK_ENABLE();
/* Set USB Interrupt priority */
HAL_NVIC_SetPriority(USB_LP_CAN1_RX0_IRQn, 7, 0);
/* Enable USB Interrupt */
HAL_NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
}
/**
* @brief De-Initializes the PCD MSP.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_MspDeInit(PCD_HandleTypeDef *hpcd)
{
/* Disable USB FS Clock */
__HAL_RCC_USB_CLK_DISABLE();
}
设置USB的硬件IO口为复用模式，并设置中断优先级且使能USB中断，USB中断号有三个：USB低优先级中断(20)，USB高优先级中断(19)，USB唤醒中断(42)，这里是使能的USB低优先级中断，所有的USB事件均可触发该中断。USB底层回调函数接口实现如下：
/*******************************************************************************
LL Driver Callbacks (PCD -> USB Device Library)
*******************************************************************************/
/**
* @brief SetupStage callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SetupStageCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SetupStage((USBD_HandleTypeDef*)hpcd->pData, (uint8_t *)hpcd->Setup);
}
/**
* @brief DataOut Stage callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_DataOutStageCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_DataOutStage((USBD_HandleTypeDef*)hpcd->pData, epnum, hpcd->OUT_ep[epnum].xfer_buff);
}
/**
* @brief DataIn Stage callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_DataInStageCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_DataInStage((USBD_HandleTypeDef*)hpcd->pData, epnum, hpcd->IN_ep[epnum].xfer_buff);
}
/**
* @brief SOF callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SOFCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SOF((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Reset callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ResetCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_SetSpeed((USBD_HandleTypeDef*)hpcd->pData, USBD_SPEED_FULL);
/* Reset Device */
USBD_LL_Reset((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Suspend callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_SuspendCallback(PCD_HandleTypeDef *hpcd)
{
/* Inform USB library that core enters in suspend Mode */
USBD_LL_Suspend((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Resume callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ResumeCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_Resume((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief ISOOUTIncomplete callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_ISOOUTIncompleteCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_IsoOUTIncomplete((USBD_HandleTypeDef*)hpcd->pData, epnum);
}
/**
* @brief ISOINIncomplete callback.
* @param hpcd: PCD handle
* @param epnum: Endpoint Number
* @retval None
*/
void HAL_PCD_ISOINIncompleteCallback(PCD_HandleTypeDef *hpcd, uint8_t epnum)
{
USBD_LL_IsoINIncomplete((USBD_HandleTypeDef*)hpcd->pData, epnum);
}
/**
* @brief ConnectCallback callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_ConnectCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_DevConnected((USBD_HandleTypeDef*)hpcd->pData);
}
/**
* @brief Disconnect callback.
* @param hpcd: PCD handle
* @retval None
*/
void HAL_PCD_DisconnectCallback(PCD_HandleTypeDef *hpcd)
{
USBD_LL_DevDisconnected((USBD_HandleTypeDef*)hpcd->pData);
}每一个回调函数都是调用的usbd_core.c中的底层函数，对于不同的USB类该回调函数的接口实现是类似的，分别对应了触发USB中断的各个情况，跟串口中断不同，串口中断我们一般关心接收和发送中断即可。而USB的中断源比较多，从回调函数的个数就可以看得出来，即使这样，但这些回调函数里面有几个是为空的，如同步传输完成的回调函数以及设备连接的回调函数，此外，HAL_PCD_IRQHandler()里是没有调用同步传输完成回调函数的，在OTG模块的中断服务例程里才有调用。既然在全速模式下回调函数为空就不必刻意关注该回调函数了。重点关注Setup、DataIn、DataOut等即可，与之相关的是USB通信中的Setup阶段、数据阶段，所有的USB通信请求都是由USB主机发起，一般分为三个阶段：设置阶段、数据阶段、状态阶段。其中数据阶段是可以省略的。具体内容在后面遇到再分析，至此，USB中断底层回调函数浏览完毕，还剩下底层的设备驱动API，在分析之前需要注意两个个重要的结构体PCD_HandleTypeDef和USBD_HandleTypeDef，前者是STM32Cube库提供的跟寄存器相关的数据结构，后者是USB器件库提供的跟USB协议相关的数据结构，在例程中两者相互引用，PCD_HandleTypeDef结构如下：
/**
* @brief PCD Handle Structure definition
*/
typedef struct
{
PCD_TypeDef *Instance; /*!< Register base address */
PCD_InitTypeDef Init; /*!< PCD required parameters */
__IO uint8_t USB_Address; /*!< USB Address: not used by USB OTG FS */
PCD_EPTypeDef IN_ep[15]; /*!< IN endpoint parameters */
PCD_EPTypeDef OUT_ep[15]; /*!< OUT endpoint parameters */
HAL_LockTypeDef Lock; /*!< PCD peripheral status */
__IO PCD_StateTypeDef State; /*!< PCD communication state */
uint32_t Setup[12]; /*!< Setup packet buffer */
void *pData; /*!< Pointer to upper stack Handler */
} PCD_HandleTypeDef;
/**
* @brief PCD State structure definition
*/
typedef enum
{
HAL_PCD_STATE_RESET = 0x00,
HAL_PCD_STATE_READY = 0x01,
HAL_PCD_STATE_ERROR = 0x02,
HAL_PCD_STATE_BUSY = 0x03,
HAL_PCD_STATE_TIMEOUT = 0x04
} PCD_StateTypeDef;
#if defined (USB)
typedef USB_TypeDef PCD_TypeDef;
typedef USB_CfgTypeDef PCD_InitTypeDef;
typedef USB_EPTypeDef PCD_EPTypeDef;
#endif /* USB */
/**
* @brief Universal Serial Bus Full Speed Device
*/
typedef struct
{
__IO uint16_t EP0R; /*!< USB Endpoint 0 register, Address offset: 0x00 */
__IO uint16_t RESERVED0; /*!< Reserved */
__IO uint16_t EP1R; /*!< USB Endpoint 1 register, Address offset: 0x04 */
__IO uint16_t RESERVED1; /*!< Reserved */
__IO uint16_t EP2R; /*!< USB Endpoint 2 register, Address offset: 0x08 */
__IO uint16_t RESERVED2; /*!< Reserved */
__IO uint16_t EP3R; /*!< USB Endpoint 3 register, Address offset: 0x0C */
__IO uint16_t RESERVED3; /*!< Reserved */
__IO uint16_t EP4R; /*!< USB Endpoint 4 register, Address offset: 0x10 */
__IO uint16_t RESERVED4; /*!< Reserved */
__IO uint16_t EP5R; /*!< USB Endpoint 5 register, Address offset: 0x14 */
__IO uint16_t RESERVED5; /*!< Reserved */
__IO uint16_t EP6R; /*!< USB Endpoint 6 register, Address offset: 0x18 */
__IO uint16_t RESERVED6; /*!< Reserved */
__IO uint16_t EP7R; /*!< USB Endpoint 7 register, Address offset: 0x1C */
__IO uint16_t RESERVED7[17]; /*!< Reserved */
__IO uint16_t CNTR; /*!< Control register, Address offset: 0x40 */
__IO uint16_t RESERVED8; /*!< Reserved */
__IO uint16_t ISTR; /*!< Interrupt status register, Address offset: 0x44 */
__IO uint16_t RESERVED9; /*!< Reserved */
__IO uint16_t FNR; /*!< Frame number register, Address offset: 0x48 */
__IO uint16_t RESERVEDA; /*!< Reserved */
__IO uint16_t DADDR; /*!< Device address register, Address offset: 0x4C */
__IO uint16_t RESERVEDB; /*!< Reserved */
__IO uint16_t BTABLE; /*!< Buffer Table address register, Address offset: 0x50 */
__IO uint16_t RESERVEDC; /*!< Reserved */
} USB_TypeDef;
#if defined (USB)
/**
* @brief USB Initialization Structure definition
*/
typedef struct
{
uint32_t dev_endpoints; /*!< Device Endpoints number.
This parameter depends on the used USB core.
This parameter must be a number between Min_Data = 1 and Max_Data = 15 */
uint32_t speed; /*!< USB Core speed.
This parameter can be any value of @ref USB_Core_Speed */
uint32_t ep0_mps; /*!< Set the Endpoint 0 Max Packet size.
This parameter can be any value of @ref USB_EP0_MPS */
uint32_t phy_itface; /*!< Select the used PHY interface.
This parameter can be any value of @ref USB_Core_PHY */
uint32_t Sof_enable; /*!< Enable or disable the output of the SOF signal. */
uint32_t low_power_enable; /*!< Enable or disable Low Power mode */
uint32_t lpm_enable; /*!< Enable or disable Battery charging. */
uint32_t battery_charging_enable; /*!< Enable or disable Battery charging. */
} USB_CfgTypeDef;
typedef struct
{
uint8_t num; /*!< Endpoint number
This parameter must be a number between Min_Data = 1 and Max_Data = 15 */
uint8_t is_in; /*!< Endpoint direction
This parameter must be a number between Min_Data = 0 and Max_Data = 1 */
uint8_t is_stall; /*!< Endpoint stall condition
This parameter must be a number between Min_Data = 0 and Max_Data = 1 */
uint8_t type; /*!< Endpoint type
This parameter can be any value of @ref USB_EP_Type */
uint16_t pmaadress; /*!< PMA Address
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint16_t pmaaddr0; /*!< PMA Address0
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint16_t pmaaddr1; /*!< PMA Address1
This parameter can be any value between Min_addr = 0 and Max_addr = 1K */
uint8_t doublebuffer; /*!< Double buffer enable
This parameter can be 0 or 1 */
uint16_t tx_fifo_num; /*!< This parameter is not required by USB Device FS peripheral, it is used
only by USB OTG FS peripheral
This parameter is added to ensure compatibility across USB peripherals */
uint32_t maxpacket; /*!< Endpoint Max packet size
This parameter must be a number between Min_Data = 0 and Max_Data = 64KB */
uint8_t *xfer_buff; /*!< Pointer to transfer buffer */
uint32_t xfer_len; /*!< Current transfer length */
uint32_t xfer_count; /*!< Partial transfer length in case of multi packet transfer */
} USB_EPTypeDef;
#endif /* USB */其中USB_TypeDef结构跟STM32寄存器相关，可通过查看STM32F103C8T6参考手册来熟悉USB相关寄存器。剩余的两个结构USB_CfgTypeDef和USB_EPTypeDef跟STM32中USB模块的特性相关，因此需要多多熟悉相对应的参考手册，STM32F103C8T6可提供16个单向端点，至于PCD_HandleTypeDef中Setup数组大小为12，还不清楚为什么是12，USB协议中Setup包大小是8个字节，而这里是48个字节，后面有眉目了再说吧。对于USB器件库的使用来说PCD_HandleTypeDef结构体没有USBD_HandleTypeDef结构体重要，USBD_HandleTypeDef结构体是USB器件库中核心结构体，如下：
/* USB Device handle structure */
typedef struct _USBD_HandleTypeDef
{
uint8_t id;
uint32_t dev_config;
uint32_t dev_default_config;
uint32_t dev_config_status;
USBD_SpeedTypeDef dev_speed;
USBD_EndpointTypeDef ep_in[15];
USBD_EndpointTypeDef ep_out[15];
uint32_t ep0_state;
uint32_t ep0_data_len;
uint8_t dev_state;
uint8_t dev_old_state;
uint8_t dev_address;
uint8_t dev_connection_status;
uint8_t dev_test_mode;
uint32_t dev_remote_wakeup;
USBD_SetupReqTypedef request;
USBD_DescriptorsTypeDef *pDesc;
USBD_ClassTypeDef *pClass;
void *pClassData;
void *pUserData;
void *pData;
} USBD_HandleTypeDef;
/* Following USB Device Speed */
typedef enum
{
USBD_SPEED_HIGH = 0,
USBD_SPEED_FULL = 1,
USBD_SPEED_LOW = 2,
}USBD_SpeedTypeDef;
/* USB Device handle structure */
typedef struct
{
uint32_t status;
uint32_t total_length;
uint32_t rem_length;
uint32_t maxpacket;
} USBD_EndpointTypeDef;
/** @defgroup USBD_DEF_Exported_TypesDefinitions
* @{
*/
typedef struct usb_setup_req
{
uint8_t bmRequest;
uint8_t bRequest;
uint16_t wValue;
uint16_t wIndex;
uint16_t wLength;
}USBD_SetupReqTypedef;
typedef struct _Device_cb
{
uint8_t (*Init) (struct _USBD_HandleTypeDef *pdev , uint8_t cfgidx);
uint8_t (*DeInit) (struct _USBD_HandleTypeDef *pdev , uint8_t cfgidx);
/* Control Endpoints*/
uint8_t (*Setup) (struct _USBD_HandleTypeDef *pdev , USBD_SetupReqTypedef *req);
uint8_t (*EP0_TxSent) (struct _USBD_HandleTypeDef *pdev );
uint8_t (*EP0_RxReady) (struct _USBD_HandleTypeDef *pdev );
/* Class Specific Endpoints*/
uint8_t (*DataIn) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*DataOut) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*SOF) (struct _USBD_HandleTypeDef *pdev);
uint8_t (*IsoINIncomplete) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t (*IsoOUTIncomplete) (struct _USBD_HandleTypeDef *pdev , uint8_t epnum);
uint8_t *(*GetHSConfigDescriptor)(uint16_t *length);
uint8_t *(*GetFSConfigDescriptor)(uint16_t *length);
uint8_t *(*GetOtherSpeedConfigDescriptor)(uint16_t *length);
uint8_t *(*GetDeviceQualifierDescriptor)(uint16_t *length);
#if (USBD_SUPPORT_USER_STRING == 1)
uint8_t *(*GetUsrStrDescriptor)(struct _USBD_HandleTypeDef *pdev ,uint8_t index, uint16_t *length);
#endif
} USBD_ClassTypeDef;一个USB总线最多可支持1128个设备，地址范围为0~127，因此这里用一个字节的dev_address来存储唯一的设备地址。而USBD_SetupReqTypedef结构体跟USB协议相关，USB协议中定义的Setup请求格式如下：
可以看到二者相匹配，获取setup请求更多详情，请参考USB2.0协议规范中第九章节。同时可以看到在USBD_HandleTypeDef结构体中包含了之前提到的描述符结构体USBD_DescriptorTypeDef，此外还包含了一个新的结构体设备类结构体USBD_ClassTypeDef，它里面是各个回调函数，在USB中断的回调函数中会调用设备类中的回调函数来实现具体功能，USB器件库手册中说明了设备类回调函数的作用，如下：
这些接口的实现是在CDC接口文件中实现，后面再分析，PCD_HandleTypeDef和USBD_HandleTypeDef结构通过void指针相互引用。
USB模块中静态空间分配方案实现如下：
/**
* @brief static single allocation.
* @param size: size of allocated memory
* @retval None
*/
void *USBD_static_malloc(uint32_t size)
{
static uint32_t mem[MAX_STATIC_ALLOC_SIZE];
return mem;
}
/**
* @brief Dummy memory free
* @param *p pointer to allocated memory address
* @retval None
*/
void USBD_static_free(void *p)
{
}实现很简单申请一块静态空间并返回给调用者。USB设备驱动的底层API实现如下：
/*******************************************************************************
LL Driver Interface (USB Device Library --> PCD)
*******************************************************************************/
/**
* @brief Initializes the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Init(USBD_HandleTypeDef *pdev)
{
/* Set LL Driver parameters */
hpcd.Instance = USB;
hpcd.Init.dev_endpoints = 8; //STM32F103C8T6Ö§³Ö8¸öË«Ïò¶Ëµã
hpcd.Init.ep0_mps = PCD_EP0MPS_64; //¶Ëµã0Ö§³ÖµÄ×î´ó·Ö×é×Ö½ÚΪ64
hpcd.Init.phy_itface = PCD_PHY_EMBEDDED;
hpcd.Init.speed = PCD_SPEED_FULL; //USB2.0È«ËÙÉ豸
hpcd.Init.low_power_enable = 0; //²»Ê¹Äܵ͹¦ºÄģʽ
/* Link The driver to the stack */
hpcd.pData = pdev;
pdev->pData = &hpcd;
/* Initialize LL Driver */
HAL_PCD_Init((PCD_HandleTypeDef*)pdev->pData);
HAL_PCDEx_PMAConfig(pdev->pData , 0x00 , PCD_SNG_BUF, 0x40); //OUT¶Ëµã
HAL_PCDEx_PMAConfig(pdev->pData , 0x80 , PCD_SNG_BUF, 0x80); //IN¶Ëµã
HAL_PCDEx_PMAConfig(pdev->pData , CDC_IN_EP , PCD_SNG_BUF, 0xC0);
HAL_PCDEx_PMAConfig(pdev->pData , CDC_OUT_EP , PCD_SNG_BUF, 0x110);
HAL_PCDEx_PMAConfig(pdev->pData , CDC_CMD_EP , PCD_SNG_BUF, 0x100);
return USBD_OK;
}
/**
* @brief De-Initializes the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_DeInit(USBD_HandleTypeDef *pdev)
{
HAL_PCD_DeInit((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Starts the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Start(USBD_HandleTypeDef *pdev)
{
HAL_PCD_Start((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Stops the Low Level portion of the Device driver.
* @param pdev: Device handle
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Stop(USBD_HandleTypeDef *pdev)
{
HAL_PCD_Stop((PCD_HandleTypeDef*)pdev->pData);
return USBD_OK;
}
/**
* @brief Opens an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param ep_type: Endpoint Type
* @param ep_mps: Endpoint Max Packet Size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_OpenEP(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t ep_type,
uint16_t ep_mps)
{
HAL_PCD_EP_Open((PCD_HandleTypeDef*)pdev->pData,
ep_addr,
ep_mps,
ep_type);
return USBD_OK;
}
/**
* @brief Closes an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_CloseEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_Close((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Flushes an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_FlushEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_Flush((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Sets a Stall condition on an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_StallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_SetStall((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Clears a Stall condition on an endpoint of the Low Level Driver.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_ClearStallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
HAL_PCD_EP_ClrStall((PCD_HandleTypeDef*)pdev->pData, ep_addr);
return USBD_OK;
}
/**
* @brief Returns Stall condition.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval Stall (1: Yes, 0: No)
*/
uint8_t USBD_LL_IsStallEP(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
PCD_HandleTypeDef *hpcd = (PCD_HandleTypeDef*)pdev->pData;
if ((ep_addr & 0x80) == 0x80)
{
return hpcd->IN_ep[ep_addr & 0x7F].is_stall;
}
else
{
return hpcd->OUT_ep[ep_addr & 0x7F].is_stall;
}
}
/**
* @brief Assigns a USB address to the device.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_SetUSBAddress(USBD_HandleTypeDef *pdev, uint8_t dev_addr)
{
HAL_PCD_SetAddress((PCD_HandleTypeDef*)pdev->pData, dev_addr);
return USBD_OK;
}
/**
* @brief Transmits data over an endpoint.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param pbuf: Pointer to data to be sent
* @param size: Data size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_Transmit(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint16_t size)
{
HAL_PCD_EP_Transmit((PCD_HandleTypeDef*)pdev->pData, ep_addr, pbuf, size);
return USBD_OK;
}
/**
* @brief Prepares an endpoint for reception.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @param pbuf: Pointer to data to be received
* @param size: Data size
* @retval USBD Status
*/
USBD_StatusTypeDef USBD_LL_PrepareReceive(USBD_HandleTypeDef *pdev,
uint8_t ep_addr,
uint8_t *pbuf,
uint16_t size)
{
HAL_PCD_EP_Receive((PCD_HandleTypeDef*)pdev->pData, ep_addr, pbuf, size);
return USBD_OK;
}
/**
* @brief Returns the last transferred packet size.
* @param pdev: Device handle
* @param ep_addr: Endpoint Number
* @retval Recived Data Size
*/
uint32_t USBD_LL_GetRxDataSize(USBD_HandleTypeDef *pdev, uint8_t ep_addr)
{
return HAL_PCD_EP_GetRxCount((PCD_HandleTypeDef*)pdev->pData, ep_addr);
}
/**
* @brief Delays routine for the USB Device Library.
* @param Delay: Delay in ms
* @retval None
*/
void USBD_LL_Delay(uint32_t Delay)
{
HAL_Delay(Delay);
}这些底层驱动的实现大部分都是调用Cube库中USB接口，其具体实现不必刻意关注，如果有空闲可以静心研究其寄存器的操作，我们一般只关心底层接口即可，比较复杂的一个接口是USBD_LL_Init()，USB中端点分为IN端点和OUT端点，共16个端点，在USB器件库中使用一个字节来表示，最高位为0是OUT端点，最高位为1是IN端点，USBD_LL_Init()中设置端点数为8，端点0最大包大小为64字节，为全速设备，不支持低功耗模式，并通过void指针pData来实现USBD_HandleTypeDef和PCD_HandleTypeDef结构的相互引用，HAL_PCDEx_PMAConfig()函数来设置端点缓冲区大小，这里使用了5个单向端点，有关分组缓冲的的描述可以在对应的参考手册上查找到，示例如下：
STM32中有单独的512个字节是作为USB分组缓冲区，该区域的地址为0x4000_6000~0x4000_63FF，USB和CAN模块共用该区域，因此二者不能同时访问，可以互斥访问，有关分组缓冲区有两类寄存器：USB分组缓冲区描述表地址寄存器(USB_BTABLE
);缓冲区描述表寄存器。如上图所示缓冲区描述表寄存器是几组寄存器的集合(一共8个端点共8组集合，每组里包含了4个寄存器：ADDRn_TX、COUNTn_TX、ADDRn_RX、COUNTn_RX)。这些寄存器的地址是可变的，在0x4000_6000~0x4000_63FF中，具体地址由USB_BTABLE寄存器指定，在本例中USB_BTABLE指定为0，如下：
#define BTABLE_ADDRESS (0x000)
/*Set Btable Address*/
USBx->BTABLE = BTABLE_ADDRESS;对于每个端点的缓冲区地址及大小则由缓冲区描述表中的对应的4个寄存器来指定。分组缓冲区的访问是32bit的，所以虽然0x4000_0000~0x4000_63FF(共1K字节)，但实际上只用了512字节。此外，这也是为何USB有两种地址表示方式，一个是USB本地地址，另一个是应用程序访问USB分组缓冲地址。在示例中设置默认的控制端点的分组大小为64字节，这也和端点0的最大包大小为64相符，且都是使用的单缓冲端点，至此，usbd_conf文件分析完毕。
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