AT32 USB_DEVICE — 复合设备: VCP + MSC

Tue, 08 Sep 2026 14:52:21 +0800

USB_DEVICE — 复合设备: VCP + MSC

固件库: AT32F403A_407_Firmware_Library V2.2.2
芯片: AT32
源文件: AT32/AT32F403A_407_Firmware_Library_V2.2.2/project/at_start_f403a/examples/usb_device/composite_vcp_msc/src/main.c

功能简介

本示例演示 USB 设备模式 — 复合设备: VCP + MSC。MCU 作为 USB 设备连接到电脑，实现 HID 键盘/鼠标、虚拟串口（CDC）、大容量存储（MSC）等功能。

完整代码

#include "at32f403a_407_board.h"
#include "at32f403a_407_clock.h"
#include "usbd_core.h"
#include "cdc_msc_class.h"
#include "cdc_msc_desc.h"
#include "usbd_int.h"

int main(void)
{
  uint16_t data_len;

  uint32_t timeout;

  uint8_t send_zero_packet = 0;

  /* config nvic priority group */
  nvic_priority_group_config(NVIC_PRIORITY_GROUP_4);

  system_clock_config();

  at32_board_init();

  /* select usb 48m clcok source */
  usb_clock48m_select(USB_CLK_HEXT);

  /* enable usb clock */
  crm_periph_clock_enable(CRM_USB_PERIPH_CLOCK, TRUE);

  /* enable usb interrupt */
  nvic_irq_enable(USBFS_L_CAN1_RX0_IRQn, 0, 0);

  /* usb core init */
  usbd_core_init(&usb_core_dev, USB, &cdc_msc_class_handler, &cdc_msc_desc_handler, 0);

  /* enable usb pull-up */
  usbd_connect(&usb_core_dev);

  while(1)
  {
    /* get usb vcp receive data */
    data_len = usb_vcp_get_rxdata(&usb_core_dev, usb_buffer);

    if(data_len > 0 || send_zero_packet == 1)
    {
      /* bulk transfer is complete when the endpoint does one of the following
         1 has transferred exactly the amount of data expected
         2 transfers a packet with a payload size less than wMaxPacketSize or transfers a zero-length packet
      */
      if(data_len > 0)
        send_zero_packet = 1;

      if(data_len == 0)
        send_zero_packet = 0;

      timeout = 5000000;
      do
      {
        /* send data to host */
        if(usb_vcp_send_data(&usb_core_dev, usb_buffer, data_len) == SUCCESS)
        {
          break;
        }
      }while(timeout --);
    }

  }
}

代码讲解

系统时钟初始化：配置 MCU 的主频和时钟树。不同芯片的时钟配置不同，一般由工具生成。

板级初始化：初始化开发板上的 LED、按键等基础外设。

中断优先级配置：NVIC 设置中断的抢占优先级和子优先级。数字越小优先级越高。

Composite_vcp_msc on CLing

AT32 USB_DEVICE — 复合设备: VCP + MSC

USB_DEVICE — 复合设备: VCP + MSC

功能简介

完整代码

代码讲解