本程序实现了主机枚举USB设备的完整过程，设备状态由Powered状态转变为最终的Configured状态，全部由STM32寄存器实现，不涉及复杂的库函数。
设备的枚举类型是USB大容量存储（Bulk Only型）。端点0为控制端点，端点1为同时用于数据发送和接收的Bulk型端点（这部分代码还没写）。
配置描述符里面interface->bNumEndpoints要写2，因为EP1_IN和EP1_OUT分别算一个端点，共两个端点（ENDP0不能写进配置描述符的端点描述符里面）。实验证明两个不同传输方向的Bulk型端点使用同一个端点号是可行的（1+31 1-36 1-13，端点1先收到CBW，再发送数据和CSW）。
Keil工程文件下载地址：https://pan.baidu.com/s/1c2yIKzY
参考文档：usb_20_081017/usb_20.pdf，请认真阅读其中的第八章，理清Bulk transfer和Control transfer的完整过程。设备描述符等数据结构请参阅第九章的表格。
电路连接：
USB接口最左侧的VBUS接+5V，通过AMS1117降压到3.3V给STM32F103C8单片机供电。D-通过22Ω的电阻接PA11，D+通过22Ω的电阻接PA12，D+还通过一个1.5kΩ的电阻接PB3，GND引脚接到单片机的GND上。
单片机晶振为8MHz，所用的串口是USART3，波特率为115200。
注意，程序中要慎用printf函数打印字符串，最好不要打印大量的字符串内容，否则由于设备响应主机不及时，USB将无法正常工作。
【main.c】
#include <stdio.h>
#include <stm32f10x.h>
#include "USB.h"
void USB_Init(void);
void dump_data(const void *data, uint16_t len)
{
const uint8_t *p = data;
while (len--)
printf("%02X", *p++);
printf("\n");
}
int fputc(int ch, FILE *fp)
{
if (fp == stdout)
{
if (ch == '\n')
{
while ((USART3->SR & USART_SR_TXE) == 0);
USART3->DR = '\r';
}
while ((USART3->SR & USART_SR_TXE) == 0);
USART3->DR = ch;
}
return ch;
}
int main(void)
{
uint8_t data;
RCC->APB1ENR = RCC_APB1ENR_USART3EN | RCC_APB1ENR_USBEN;
RCC->APB2ENR = RCC_APB2ENR_AFIOEN | RCC_APB2ENR_IOPAEN | RCC_APB2ENR_IOPBEN;
AFIO->MAPR = AFIO_MAPR_SWJ_CFG_JTAGDISABLE; // 使用SWD调试接口, 禁用JTAG
// USB引脚PA11~12无需配置
GPIOB->BSRR = GPIO_BSRR_BS3; // PB3设为高电平
GPIOB->CRH = 0x44444b44; // 串口发送引脚PB10设为复用推挽输出
GPIOB->CRL = 0x44483444; // PB3为USB_DP上的上拉电阻, 高电平表明设备插入主机
// USB_DP上的上拉电阻最好不要直接接高电平, 而是接到某个I/O口上(这里是PB3), 方便查看调试信息, 避免USB线拔来拔去
USART3->BRR = 312; // 波特率: 115200
USART3->CR1 = USART_CR1_UE | USART_CR1_TE | USART_CR1_RE;
printf("STM32F103C8 USB\n");
USB_Init();
while (1)
{
if (USART3->SR & USART_SR_RXNE)
{
data = USART3->DR;
if (data == 'u')
printf("USB->EP0R=0x%04x, USB->EP1R=0x%04x, USB->ISTR=0x%04x, USB->CNTR=0x%04x\n", USB->EP0R, USB->EP1R, USB->ISTR, USB->CNTR);
}
}
}【USB.h】
// STM32 CubeMX头文件中复制过来的USB寄存器定义
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;
/* USB device FS */
#define USB_BASE (APB1PERIPH_BASE + 0x00005C00U) /*!< USB_IP Peripheral Registers base address */
#define USB_PMAADDR (APB1PERIPH_BASE + 0x00006000U) /*!< USB_IP Packet Memory Area base address */
#define USB ((USB_TypeDef *)USB_BASE)
// 对于单向双缓冲型的发送端点, 寄存器名称后缀都是TX; 单向双缓冲接收端点则都是RX
typedef struct
{
__IO uint16_t ADDR_TX;
__IO uint16_t RESERVED0;
__IO uint16_t COUNT_TX;
__IO uint16_t RESERVED1;
__IO uint16_t ADDR_RX;
__IO uint16_t RESERVED2;
__IO uint16_t COUNT_RX;
__IO uint16_t RESERVED3;
} USB_BufferDescriptor;
#define USB_BufDesc ((USB_BufferDescriptor *)(USB_PMAADDR + USB->BTABLE))
#define USB_ISTR_MASK 0x7f00
#define USB_EPnR_MASK_T 0x8f8f // 防止翻转位发生翻转用的掩码
#define USB_EPnR_MASK_CW0 0x8080 // 防止rc_w0型的位被清零
#define USB_EPnR(reg) ((reg & USB_EPnR_MASK_T) | USB_EPnR_MASK_CW0)
typedef __packed struct
{
uint8_t bmRequestType;
uint8_t bRequest;
uint16_t wValue;
uint16_t wIndex;
uint16_t wLength;
} USB_DeviceRequest;
typedef __packed struct
{
uint8_t bLength;
uint8_t bDescriptorType;
uint16_t bcdUSB;
uint8_t bDeviceClass;
uint8_t bDeviceSubClass;
uint8_t bDeviceProtocol;
uint8_t bMaxPacketSize0;
uint16_t idVendor;
uint16_t idProduct;
uint16_t bcdDevice;
uint8_t iManufacturer;
uint8_t iProduct;
uint8_t iSerialNumber;
uint8_t bNumConfigurations;
} USB_DeviceDescriptor;
typedef __packed struct
{
uint8_t bLength;
uint8_t bDescriptorType;
uint16_t wTotalLength;
uint8_t bNumInterfaces;
uint8_t bConfigurationValue;
uint8_t iConfiguration;
uint8_t bmAttributes;
uint8_t bMaxPower;
} USB_ConfigurationDescriptor;
typedef __packed struct
{
uint8_t bLength;
uint8_t bDescriptorType;
uint8_t bInterfaceNumber;
uint8_t bAlternateSetting;
uint8_t bNumEndpoints;
uint8_t bInterfaceClass;
uint8_t bInterfaceSubClass;
uint8_t bInterfaceProtocol;
uint8_t iInterface;
} USB_InterfaceDescriptor;
typedef __packed struct
{
uint8_t bLength;
uint8_t bDescriptorType;
uint8_t bEndpointAddress;
uint8_t bmAttributes;
uint16_t wMaxPacketSize;
uint8_t bInterval;
} USB_EndpointDescriptor;
typedef __packed struct
{
uint8_t bLength;
uint8_t bDescriptorType;
uint16_t wData[1];
} USB_StringDescriptor;【usb_def.h】
/**
******************************************************************************
* @file usb_def.h
* @author MCD Application Team
* @version V4.1.0
* @date 26-May-2017
* @brief Definitions related to USB Core
******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT(c) 2017 STMicroelectronics</center></h2>
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
*/
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __USB_DEF_H
#define __USB_DEF_H
/* Includes ------------------------------------------------------------------*/
/* Exported types ------------------------------------------------------------*/
typedef enum _RECIPIENT_TYPE
{
DEVICE_RECIPIENT, /* Recipient device */
INTERFACE_RECIPIENT, /* Recipient interface */
ENDPOINT_RECIPIENT, /* Recipient endpoint */
OTHER_RECIPIENT
} RECIPIENT_TYPE;
typedef enum _STANDARD_REQUESTS
{
GET_STATUS = 0,
CLEAR_FEATURE,
RESERVED1,
SET_FEATURE,
RESERVED2,
SET_ADDRESS,
GET_DESCRIPTOR,
SET_DESCRIPTOR,
GET_CONFIGURATION,
SET_CONFIGURATION,
GET_INTERFACE,
SET_INTERFACE,
TOTAL_sREQUEST, /* Total number of Standard request */
SYNCH_FRAME = 12
} STANDARD_REQUESTS;
/* Definition of "USBwValue" */
typedef enum _DESCRIPTOR_TYPE
{
DEVICE_DESCRIPTOR = 1,
CONFIG_DESCRIPTOR,
STRING_DESCRIPTOR,
INTERFACE_DESCRIPTOR,
ENDPOINT_DESCRIPTOR,
DEVICE_BOS_DESCRIPTOR = 0xF
} DESCRIPTOR_TYPE;
/* Feature selector of a SET_FEATURE or CLEAR_FEATURE */
typedef enum _FEATURE_SELECTOR
{
ENDPOINT_STALL,
DEVICE_REMOTE_WAKEUP
} FEATURE_SELECTOR;
/* Exported constants --------------------------------------------------------*/
/* Definition of "USBbmRequestType" */
#define REQUEST_TYPE 0x60 /* Mask to get request type */
#define STANDARD_REQUEST 0x00 /* Standard request */
#define CLASS_REQUEST 0x20 /* Class request */
#define VENDOR_REQUEST 0x40 /* Vendor request */
#define RECIPIENT 0x1F /* Mask to get recipient */
/* Exported macro ------------------------------------------------------------*/
/* Exported functions ------------------------------------------------------- */
#endif /* __USB_DEF_H */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
【usb_test.c】
#include <stdio.h>
#include <stm32f10x.h>
#include <wchar.h>
#include "USB.h"
#include "usb_def.h"
void dump_data(const void *data, uint16_t len);
void USB_ReadPMA(uint16_t offset, void *buffer, uint16_t len);
void USB_WritePMA(uint16_t usbaddr, const void *buffer, uint16_t len);
static void USB_GetDescriptor(const USB_DeviceRequest *devreq);
// Keil MDK使用微库时, 下面两个函数必须自己实现
wchar_t *wcscpy(wchar_t *s1, const wchar_t *s2) // 复制UTF-16字符串
{
wchar_t *r = s1;
while ((*r++ = *s2++) != 0);
return s1;
}
size_t wcslen(const wchar_t *s) // 求UTF-16字符串的长度
{
size_t n = 0;
while (*s++)
n++;
return n;
}
void USB_CorrectTransfer(void)
{
static uint8_t pending_addr = 0;
uint8_t buffer[64];
uint8_t ep_id;
uint16_t len;
USB_DeviceRequest *devreq = (USB_DeviceRequest *)buffer;
ep_id = USB->ISTR & USB_ISTR_EP_ID; // 端点号
if (ep_id == 0)
{
if (USB->ISTR & USB_ISTR_DIR)
{
// 端点0接收成功
//if (USB->EP0R & USB_EP0R_SETUP)
// printf("[SETUP]\n");
USB->EP0R = USB_EPnR(USB->EP0R) & ~USB_EP0R_CTR_RX; // 清除中断标志位
len = USB_BufDesc[0].COUNT_RX & USB_COUNT0_RX_COUNT0_RX; // 收到的字节数
printf("0+%d\n", len);
if (len > 0)
{
USB_ReadPMA(USB_BufDesc[0].ADDR_RX, buffer, len);
dump_data(buffer, len);
if ((devreq->bmRequestType & REQUEST_TYPE) == STANDARD_REQUEST && (devreq->bmRequestType & RECIPIENT) == DEVICE_RECIPIENT) // 标准设备请求
{
switch (devreq->bRequest)
{
case GET_DESCRIPTOR:
USB_GetDescriptor(devreq);
break;
case SET_ADDRESS:
pending_addr = devreq->wValue; // 先暂存USB设备地址, 必须等到Status stage结束后才能写入USB->DADDR寄存器中
USB_BufDesc[0].COUNT_TX = 0;
USB->EP0R = USB_EPnR(USB->EP0R) | ((USB->EP0R & USB_EP0R_STAT_TX) ^ USB_EP0R_STAT_TX); // TX=VALID
break;
case SET_CONFIGURATION:
printf("CFG%hd\n", devreq->wValue);
USB_BufDesc[0].COUNT_TX = 0;
USB->EP0R = USB_EPnR(USB->EP0R) | ((USB->EP0R & USB_EP0R_STAT_TX) ^ USB_EP0R_STAT_TX); // TX=VALID
break;
default:
dump_data(buffer, len);
}
}
else
dump_data(buffer, len);
}
else
{
// 收到一个空包
// RX=VALID, TX=NAK, STATUS_OUT=0
USB->EP0R = (USB_EPnR(USB->EP0R) & ~USB_EP0R_EP_KIND) | ((USB->EP0R & (USB_EP0R_STAT_RX | USB_EP0R_STAT_TX)) ^ (USB_EP0R_STAT_RX | USB_EP0R_STAT_TX_1));
}
}
else
{
// 端点0发送成功
USB->EP0R = USB_EPnR(USB->EP0R) & ~USB_EP0R_CTR_TX;
// 当data stage的最后一个transaction为IN token时(在本程序中所有的control transfer的data stage都最多只有一个transaction), 应将STATUS_OUT置位
// 这样在接下来的status stage的data phase中如果主机发送的数据长度不为0, 则设备不会回应ACK, 而是报告错误
len = USB_BufDesc[0].COUNT_TX;
if (len != 0)
USB->EP0R = USB_EPnR(USB->EP0R) | USB_EP0R_EP_KIND; // STATUS_OUT=1
USB->EP0R = USB_EPnR(USB->EP0R) | ((USB->EP0R & USB_EP0R_STAT_RX) ^ USB_EP0R_STAT_RX); // RX=VALID
if (pending_addr != 0)
{
// 主机在某个control transfer的data stage期间将分配的设备地址发送给设备
// 但设备必须在status stage完成后才将地址写入寄存器
USB->DADDR = USB_DADDR_EF | pending_addr;
printf("DADDR_%02X\n", pending_addr);
pending_addr = 0;
}
printf("0-%d\n", len);
}
}
else if (ep_id == 1)
{
if (USB->ISTR & USB_ISTR_DIR)
{
// 端点1接收成功
USB->EP1R = USB_EPnR(USB->EP1R) & ~USB_EP1R_CTR_RX;
len = USB_BufDesc[1].COUNT_RX & USB_COUNT1_RX_COUNT1_RX; // 收到的字节数
printf("1+%d\n", len);
if (len > 0)
{
USB_ReadPMA(USB_BufDesc[1].ADDR_RX, buffer, len);
dump_data(buffer, len);
}
USB->EP1R = USB_EPnR(USB->EP1R) | ((USB->EP1R & USB_EP1R_STAT_RX) ^ USB_EP1R_STAT_RX);
}
else
{
// 端点1发送成功
}
}
}
static void USB_GetDescriptor(const USB_DeviceRequest *devreq)
{
uint8_t buffer[64];
uint8_t type = devreq->wValue >> 8; // 高8位为请求的描述符类型
USB_ConfigurationDescriptor *config = (USB_ConfigurationDescriptor *)buffer;
USB_DeviceDescriptor *device = (USB_DeviceDescriptor *)buffer;
USB_EndpointDescriptor *endpoints;
USB_InterfaceDescriptor *interface;
USB_StringDescriptor *str = (USB_StringDescriptor *)buffer;
switch (type)
{
case DEVICE_DESCRIPTOR:
device->bLength = sizeof(USB_DeviceDescriptor);
device->bDescriptorType = DEVICE_DESCRIPTOR;
device->bcdUSB = 0x200; // USB 2.0
device->bDeviceClass = 0;
device->bDeviceSubClass = 0;
device->bDeviceProtocol = 0;
device->bMaxPacketSize0 = 64;
device->idVendor = 0x483; // STMicroelectronics (http://www.linux-usb.org/usb.ids)
device->idProduct = 0x5720; // STM microSD Flash Device
device->bcdDevice = 0x200;
device->iManufacturer = 1; // 制造商名称字符串序号
device->iProduct = 2; // 产品名字符串序号
device->iSerialNumber = 3; // 产品序列号字符串序号
device->bNumConfigurations = 1; // 配置数
USB_BufDesc[0].COUNT_TX = device->bLength;
break;
case CONFIG_DESCRIPTOR:
config->bLength = sizeof(USB_ConfigurationDescriptor);
config->bDescriptorType = CONFIG_DESCRIPTOR;
config->wTotalLength = sizeof(USB_ConfigurationDescriptor) + sizeof(USB_InterfaceDescriptor) + 2 * sizeof(USB_EndpointDescriptor);
config->bNumInterfaces = 1; // 接口数
config->bConfigurationValue = 1; // 此配置的编号
config->iConfiguration = 0; // 配置名字符串序号(0表示没有)
config->bmAttributes = 0xc0; // self-powered
config->bMaxPower = 50; // 最大电流: 100mA
interface = (USB_InterfaceDescriptor *)(config + 1);
interface->bLength = sizeof(USB_InterfaceDescriptor);
interface->bDescriptorType = INTERFACE_DESCRIPTOR;
interface->bInterfaceNumber = 0; // 此接口的编号
interface->bAlternateSetting = 0; // 可用的备用接口编号
interface->bNumEndpoints = 2; // 除了端点0外, 此接口还需要的端点数
interface->bInterfaceClass = 0x08; // Mass Storage devices
interface->bInterfaceSubClass = 0x06; // SCSI transparent command set
interface->bInterfaceProtocol = 0x50; // USB Mass Storage Class Bulk-Only (BBB) Transport
interface->iInterface = 4; // 接口名称字符串序号
endpoints = (USB_EndpointDescriptor *)(interface + 1);
endpoints[0].bLength = sizeof(USB_EndpointDescriptor);
endpoints[0].bDescriptorType = ENDPOINT_DESCRIPTOR;
endpoints[0].bEndpointAddress = 0x81; // IN, address 1
endpoints[0].bmAttributes = 0x02; // Bulk
endpoints[0].wMaxPacketSize = 64;
endpoints[0].bInterval = 0; // Does not apply to Bulk endpoints
endpoints[1].bLength = sizeof(USB_EndpointDescriptor);
endpoints[1].bDescriptorType = ENDPOINT_DESCRIPTOR;
endpoints[1].bEndpointAddress = 0x01; // OUT, address 1
endpoints[1].bmAttributes = 0x02; // Bulk
endpoints[1].wMaxPacketSize = 64;
endpoints[1].bInterval = 0;
USB_BufDesc[0].COUNT_TX = config->wTotalLength;
break;
case STRING_DESCRIPTOR:
str->bDescriptorType = STRING_DESCRIPTOR;
if (devreq->wIndex == 0x409) // 字符串英文内容
{
// 字符串的编码为UTF-16
switch (devreq->wValue & 0xff) // 低8位为字符串序号
{
case 1:
wcscpy((wchar_t *)str->wData, L"Hello Manufacturer!");
break;
case 2:
wcscpy((wchar_t *)str->wData, L"Hello Product!");
break;
case 3:
wcscpy((wchar_t *)str->wData, L"Hello SerialNumber!");
break;
case 4:
wcscpy((wchar_t *)str->wData, L"Hello Interface!");
break;
default:
printf("STR_%d\n", devreq->wValue & 0xff);
wcscpy((wchar_t *)str->wData, L"???");
}
str->bLength = 2 + wcslen((wchar_t *)str->wData) * 2;
}
else if (devreq->wIndex == 0) // 字符串语言列表
{
str->bLength = 4;
str->wData[0] = 0x0409; // English (United States)
}
else
{
printf("IND%hd\n", devreq->wIndex);
return;
}
USB_BufDesc[0].COUNT_TX = str->bLength;
break;
default:
// 包括Device qualifier (full-speed设备不支持)
USB->EP0R = USB_EPnR(USB->EP0R) | ((USB->EP0R & USB_EP0R_STAT_TX) ^ USB_EP0R_STAT_TX_0); // STAT_TX设为STALL
return;
}
// 发送的字节数不能超过主机要求的最大长度
if (USB_BufDesc[0].COUNT_TX > devreq->wLength)
USB_BufDesc[0].COUNT_TX = devreq->wLength; // 只修改发送长度, 内容原封不动, 切记!!!!
// 比如在请求字符串语言列表时, 待发送的数据量是str->bLength=4
// 如果主机要求最大只能发送devreq->wLength=2字节, 则数据内容str->bLength应该仍为4, 不能改成2
USB_WritePMA(USB_BufDesc[0].ADDR_TX, buffer, USB_BufDesc[0].COUNT_TX);
USB->EP0R = USB_EPnR(USB->EP0R) | ((USB->EP0R & USB_EP0R_STAT_TX) ^ USB_EP0R_STAT_TX); // STAT_TX设为VALID, 允许发送; STAT_RX保持NAK
}
void USB_Init(void)
{
USB->CNTR |= USB_CNTR_ERRM; // 打开错误提示中断
NVIC_EnableIRQ(USB_LP_CAN1_RX0_IRQn);
USB->CNTR &= ~USB_CNTR_PDWN; // 先打开USB外设 (需要一定的启动时间)
USB->CNTR &= ~USB_CNTR_FRES; // 撤销USB外设的复位信号
// 初始化端点0和端点1的缓冲区
USB_BufDesc[0].ADDR_TX = 112;
USB_BufDesc[0].COUNT_TX = 0;
USB_BufDesc[0].ADDR_RX = 176;
USB_BufDesc[0].COUNT_RX = USB_COUNT0_RX_BLSIZE | USB_COUNT0_RX_NUM_BLOCK_0; // 64 bytes (See Table 177. Definition of allocated buffer memory)
USB_BufDesc[1].ADDR_TX = 240;
USB_BufDesc[1].COUNT_TX = 0;
USB_BufDesc[1].ADDR_RX = 304;
USB_BufDesc[1].COUNT_RX = USB_COUNT1_RX_BLSIZE | USB_COUNT1_RX_NUM_BLOCK_0;
USB->CNTR |= USB_CNTR_RESETM; // 打开复位中断, 开始处理复位请求
}
void USB_ReadPMA(uint16_t usbaddr, void *buffer, uint16_t len)
{
const uint16_t *ppma;
uint16_t *pbuf;
// USBPMA地址范围: 0~511, 对应的APB绝对地址范围为0x40006000~0x400063fd
// 0对应0x40006000, 1对应0x40006001; 但2对应0x40006004, 3对应0x40006005, 4对应0x40006008, 5对应0x40006009
if (usbaddr % 2 == 1)
{
*(uint8_t *)buffer = *(uint8_t *)(USB_PMAADDR + 2 * usbaddr - 1);
pbuf = (uint16_t *)((uint8_t *)buffer + 1);
usbaddr++;
len--;
}
else
pbuf = (uint16_t *)buffer;
ppma = (const uint16_t *)(USB_PMAADDR + usbaddr * 2); // 将USB地址转换为APB绝对地址
while (len >= 2)
{
*pbuf = *ppma;
pbuf++; // 缓冲区地址前进2个地址
ppma += 2; // APB绝对地址前进2个地址
len -= 2;
}
if (len == 1)
*(uint8_t *)pbuf = *(uint8_t *)ppma;
}
void USB_WritePMA(uint16_t usbaddr, const void *buffer, uint16_t len)
{
const uint16_t *pbuf;
uint16_t *ppma;
if (usbaddr % 2 == 1)
{
*(uint8_t *)(USB_PMAADDR + 2 * usbaddr - 1) = *(uint8_t *)buffer;
pbuf = (uint16_t *)((uint8_t *)buffer + 1);
usbaddr++;
len--;
}
else
pbuf = (uint16_t *)buffer;
ppma = (uint16_t *)(USB_PMAADDR + usbaddr * 2);
while (len >= 2)
{
*ppma = *pbuf;
pbuf++;
ppma += 2;
len -= 2;
}
if (len == 1)
*(uint8_t *)ppma = *(uint8_t *)pbuf;
}
void USB_LP_CAN1_RX0_IRQHandler(void)
{
if (USB->ISTR & USB_ISTR_ERR)
{
USB->ISTR = USB_ISTR_MASK & ~USB_ISTR_ERR;
printf("USB error!\n"); // CRC校验错误会产生这个中断, 但系统会自动重传数据, 软件无需理会
}
if (USB->ISTR & USB_ISTR_RESET)
{
// USB复位会使DADDR和EPnR寄存器清零
USB->ISTR = USB_ISTR_MASK & ~USB_ISTR_RESET;
USB->DADDR = USB_DADDR_EF; // 启动USB外设的功能
USB->EP0R = USB_EP0R_STAT_RX | USB_EP0R_EP_TYPE_0 | USB_EP0R_STAT_TX_1; // STAT_RX=VALID, EP_TYPE=CONTROL, STAT_TX=NAK
USB->EP1R = USB_EP1R_STAT_RX | USB_EP1R_STAT_TX_1 | 1;
printf("USB reset!\n");
}
if (USB->ISTR & USB_ISTR_CTR) // 虽然CTR中断在寄存器中并没有使能, 但是仍能触发, 所以这个中断是关不掉的
USB_CorrectTransfer();
}
【程序运行结果】
USB线插到电脑上后，电脑先给一个名叫“Hello Product!”的设备安装驱动，设备的状态最开始是正常的，但最后提示驱动安装失败，设备无法启动。
串口输出结果分析：
STM32F103C8 USB USB reset! // STM32 USB外设本身的复位 (先清除PDWN位, 再清除FRES位), 此时设备为Powered状态 USB reset! // 主机让USB设备复位, 设备由Powered状态转变为Default状态 0+8 // 端点0收到8字节数据 (Setup stage: hostOUT+hostData+deviceACK) 8006000100004000 // 主机请求设备描述符, 请求的最大数据长度为0x40=64字节 0-18 // 端点0发出18字节的设备描述符数据 (Data stage: hIN+dData+hACK) 0+0 // 主机确认收到数据 (Status stage: hOUT+hDATA+dACK) USB reset! // 主机再次让USB设备复位 0+8 0005130000000000 // 主机给USB设备分配设备地址0x13, 不请求数据 (Setup stage: hOUT+hData+dACK) DADDR_13 0-0 // 设备确认收到数据, 并修改设备地址为0x13 (Status stage: hIN+dData+hACK), 设备由Default状态转变为Address状态 0+8 8006000100001200 // 主机再次请求设备描述符, 最大数据长度为0x12=18字节 0-18 // 设备通过端点0发送18字节的设备描述符 0+0 // 主机确认收到数据 0+8 800600020000FF00 // 主机请求配置描述符 0-32 // 设备发送32字节的配置描述符，顺带将接口描述符和端点描述符也发送给主机（USB规范要求） 0+0 // 主机确认 0+8 800600030000FF00 // 主机请求字符串的语言列表 0-4 // 设备告诉主机, 设备只支持0x0409 English (United States)这一种语言 0+0 0+8 800603030904FF00 // 主机请求3号字符串用0x0409这个语言(英语)写的内容 0-40 // 设备发送字符串内容 0+0 0+8 8006000600000A00 // 主机请求Device qualifier描述符, 但由于USB规范规定USB全速设备不支持这个描述符, 所以直接STALL, 向主机报告错误 0+8 8006000100001200 // 主机再次请求18字节的设备描述符 0-18 0+0 0+8 8006000200000900 // 主机请求配置描述符, 但这次只允许设备发送9字节的内容 0-9 // 配置描述符共有32字节, 设备只发送前9字节给主机, 发送的内容不作任何修改(wTotalLength=32, 绝对不允许改成9) 0+0 // 主机确认收到数据 0+8 8006000200002000 // 主机再次请求配置描述符, 最大长度改成了0x20=32字节 0-32 // 设备发送了完整的配置描述符 0+0 0+8 8006000300000200 // 主机请求字符串语言列表, 但只允许设备发送2字节的内容 (实际上就是要获取语言列表的长度) 0-2 // 语言列表共有4字节, 设备只发送前两字节, 内容中的bLength=4保持不变 0+0 0+8 8006000300000400 // 主机请求字符串语言列表, 最大长度改成了4字节 0-4 // 设备发送了完整的语言列表 0+0 0+8 8006030309040200 // 主机请求3号字符串的英语内容的长度 0-2 0+0 0+8 8006030309042800 // 主机请求3号字符串的英语内容 0-40 0+0 0+8 0009010000000000 // 应用1号配置, 设备现在由Address状态转变为最终的Configured状态 CFG1 0-0 0+8 A1FE000000000100 // 后面的代码还没写, 因为调用了两次dump_data, 所以数据内容输出了两次 A1FE000000000100 // A1表示: 方向为从设备到主机, 获取大容量存储Class的接口(Interface)信息 0+8 A1FE000000000100 A1FE000000000100 0+8 A1FE000000000100 A1FE000000000100 1+31 // 端点1收到了31字节的数据 5553424310109C112400000080000612000000240000000000000000000000 USB reset! // 端点没有回应, 所以主机认为出错了, 因此就发送了复位请求 USB reset! 0+8 8006000100004000 0-18 0+0 0+8 0005140000000000 DADDR_14 0-0 0+8 8006000100001200 0-18 0+0 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 0+8 0005160000000000 DADDR_16 0-0 0+8 8006000100001200 0-18 0+0 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 0+8 0005170000000000 DADDR_17 0-0 0+8 8006000100001200 0-18 0+0 0+8 800600020000FF00 0-32 0+0 0+8 0009010000000000 CFG1 0-0 1+31 555342431010AF0D2400000080000612000000240000000000000000000000 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 0+8 0005180000000000 DADDR_18 0-0 0+8 8006000100001200 0-18 0+0 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 USB reset! USB reset! 0+8 8006000100004000 0-18 0+0 0+8 00051A0000000000 DADDR_1A 0-0 0+8 8006000100001200 0-18 0+0 0+8 800600020000FF00 0-32 0+0