With this I’m ready to use the USB CDC. Below is an example code using it:

static uint8_t cdc_buffer[USB1_DATA_BUFF_SIZE];
static uint8_t in_buffer[USB1_DATA_BUFF_SIZE];
 
static void CDC_Run(void) {
  int i, cnt = 0;
  uint32_t val = 0;
  unsigned char buf[16];
 
  for(;;) {
    while(CDC1_App_Task(cdc_buffer, sizeof(cdc_buffer))==ERR_BUSOFF) {
      /* device not enumerated */
      LED1_Neg(); LED2_Off();
      WAIT1_Waitms(10);
    }
    LED1_Off(); LED2_Neg();
    if (CDC1_GetCharsInRxBuf()!=0) {
      i = 0;
      while(   i<sizeof(in_buffer)-1
            && CDC1_GetChar(&in_buffer[i])==ERR_OK
           )
      {
        i++;
      }
      in_buffer[i] = '\0';
      (void)CDC1_SendString((unsigned char*)"echo: ");
      (void)CDC1_SendString(in_buffer);
      UTIL1_strcpy(buf, sizeof(buf), (unsigned char*)"val: ");
      UTIL1_strcatNum32u(buf, sizeof(buf), val);
      UTIL1_strcat(buf, sizeof(buf), (unsigned char*)"\r\n");
      (void)CDC1_SendString(buf);
      val++;
    } else {
      WAIT1_Waitms(10);
      cnt++;
      if ((cnt%1024)==0) { /* from time to time, write some text */
        (void)CDC1_SendString((unsigned char*)"Type some text and it will echo.\r\n");
        CDC1_SendBlock((unsigned char*)"hello?\r\n", sizeof("hello?\r\n")-1);
      }
    }
  }
}

With this, USB CDC enumerates and runs with the K64F :-).

Test Program for USB CDC on FRDM-K64F

Summary

Sometimes it takes a long time for a break through, as in this case. And as in this case, the right hint can come from somebody else. A big “thank you” to ‘Obi’!!!! I’m sure many other users of the FRDM-K64F board have waiting for that USB working.

An example project for KDS V1.1.1 is available on GitHub.

Happy USBing ?