STM32F4 printf und trace_printf

int _write(int fd, char *str, int len) {

  // todo: implement your printf()-interface here!

  // use USART for printf!

  /**/

  ELWMD_USART2_SendStream((uint8_t*)str, len);

  return len;

  // use USB for printf!

/*

  // check for connection

  ELWMD_UsbVcp_Status_t Con = ELWMD_UsbVcp_GetStatus();

  if ((Con == ELWMD_UsbVcp_Connected) || (Con == ELWMD_UsbVcp_NewConfig)) {

    // termiate string with /0

    //str[len] = 0;

    // standard string should already be terminated by \0!

    ELWMD_UsbVcp_SendData((uint8_t*)str);

    return len;

  }

*/

  // use ethernet for printf!

  /*

  not yet implemented

  */

  return 0;

}