printf over USB VCP

[lowpowermcu]

Posted on June 19, 2014 at 13:37

Hi all,

I am trying to retarget printf over USB-VCP and I am stcuk !I implemented the putc function in the following way:****************************************int fputc(int ch, FILE *f){  USBD_CDC_SetTxBuffer(&hUSBDDevice, (uint8_t *)&ch, 1);  if(USBD_CDC_TransmitPacket(&hUSBDDevice) != USBD_OK)  {    /* Device is busy */    /* what should I return ? */  }  return ch;}*****************************************As you know fputc is called by printf for printing a single character and it is called in a loop until all characters are printed.What I am facing is that it may happen the USB is busy while sending the previous character. What do I have to do at this condition? fputc return -1 ?PS: I am STM32 Cube V2.0.0 ''18-February-2014''Thanks #usb-vcp-printf

[Tesla DeLorean]

Posted on June 19, 2014 at 16:37

Consider whether you can buffer outgoing characters, send multiple at a time, or wait until a later time if the USB is currently busy.