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USB CDC based on STM32F103 has different transmission effect on Windows7 and Ubuntu

Question asked by Zhonghao Huang on May 29, 2018
Latest reply on May 31, 2018 by Zhonghao Huang

I used STM32F103 to send data to the PC via USB CDC at a frequency of 4000Hz, 21 bytes per packet. The code generated by STMCube. And then I found that only 1000 packets can be received per second on Windows7 via serial assistant, but it can normally receive 4000 packets per second on Ubuntu via CuteCOM. How do I achieve the same effect on Windows7? Thank you.

 

int main(void)
{
     HAL_Init();
     SystemClock_Config();
     MX_GPIO_Init();
     MX_USB_DEVICE_Init();
     while(1)
     {
         __WFI();
     }
}
void HAL_SYSTICK_Callback(void)      //4000Hz
{
     CDC_Transmit_FS(buff, 21);
}

I use python to test, and the result is: 

 

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