Can not use MCO output in VirtualComport_Loopback project

[chenbo]

Posted on April 25, 2014 at 15:16

Hi, all,

    I use STM32F103VCT6 and VirtualComport_Loopback project for usb communication, the usb part works fine.     Now, I try to output the MCO at PA8, failed.void MCO_Config(void){ GPIO_InitTypeDef is;  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE); is.GPIO_Pin = GPIO_Pin_8; is.GPIO_Speed = GPIO_Speed_50MHz; is.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_Init(GPIOA,&is); RCC_MCOConfig(RCC_MCO_SYSCLK); return;}int main(void){  Set_System();  Set_USBClock();  USB_Interrupts_Config();  USB_Init();   MCO_Config();    while (1)  {    if (bDeviceState == CONFIGURED)    {      CDC_Receive_DATA();      /*Check to see if we have data yet */      if (Receive_length  != 0)      {        if (packet_sent == 1)          CDC_Send_DATA ((unsigned char*)Receive_Buffer,Receive_length);        Receive_length = 0;      }    }  }}    If I add a breakpoint before while loop, i got MCO at PA8, but ,when I continue, the MCO will disappear.  I do find that the RCC->CFGR had been changed somewhere, but I can not find it.      Anyone can give me help ?  Thanks a lot.   BTW, the Virtualcomport_lookback project comes from STM32_USB-FS-Device_Lib_v4.0.0.  #mco-vcp-usb-stm32f103vct6

[Tesla DeLorean]

Posted on April 25, 2014 at 15:33

[DEAD LINK /public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/STM32F103%20%20can%27t%20%20config%20MCO%EF%BC%88PA8%EF%BC%89%20and%20USB%20CLK%20together&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD06506F5B&TopicsView=https%3a//my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/AllItems.aspx&currentviews=23]Related?

Perhaps you should just enable the MCO after the USB clock? Perhaps your debugger is breaking things? The USB clock selection using bit-banding, not sure it should matter, you could away access the register directly. RCC->CFGR |= (1 << 22); //??

[chenbo]

Posted on April 26, 2014 at 15:58

Thanks for your help.

We found problem happended in the usb configure process.Problem solved by:    while (1)    { if (bDeviceState == CONFIGURED)  { MCO_Config(); break; }     }     while (1)  { ...}