STM32F4 Development Notes 8: Solving the USB CDC "The device cannot start" problem

    I have debugged the USB CDC device of STM32 many times. You can look at the logs written earlier. I have debugged different STM32 MCUs. I thought STM32F4 would be very simple, but it was full of pitfalls. I debugged it until midnight to solve the problem. I sorted out the problem again.

    The chip I am using now is STM32F401. In STM32CubeMX, follow the steps below to set it up.

    1. Set as full-speed slave device and do not perform USB power detection.

    2. Enable CDC and use the default settings for other settings.

    After downloading the program generated according to the above settings to the chip and connecting it to the computer, the default is as follows

    Looking closely at the details, the problem is this

    I have been searching for a long time but couldn't solve the problem. There is a saying on the Internet that you can change the usbd_conf.h file, as shown in the figure below, and set USBD_MAX_NUM_CONFIGURATION to 2. After using this method, the computer can recognize the device normally, but cannot complete the communication operation.

    There is really no other way, so I tried to adjust the stack value, which was solved by chance. The value I adjusted now is as follows, which is in the startup_stm32f401xc.s file.

    Now the communication is normal, as shown below.

    The main logic code is as follows:

int main(void)

{

uint8_t data[10] = {0,1,2,3,4,5,6,7,8,9};

  MX_ADC1_Init();

  MX_SPI1_Init();

  MX_USB_DEVICE_Init();

  while (1)

  {

if (Target.IsbMilliSecond_1000() == TRUE)

{

//¹¤×÷ָʾµÆ

Target.HAL.LED.Turn();

CDC_Transmit_FS(data, 10);

}

  }

}

    This adjustment method is too difficult, and STM32CubeMX needs to be improved.