Undefined symbol Driver_USARTn (referred from usbd_user_cdc_acm_9.o)

Hi again Andy,

I have been improving my code, and I am now at the point that I am able to receive characters from the host (PC). My problem now is that I don't understand how the function "USBD_CDCn_ACM_SendData" works.

My purpose is to include the function "USBD_CDC_ACM_WriteData" inside "SendData" function. I know that WriteData is an asynchronous function, but it never interrupts the program.

My code is:

// Called when when all data was sent.
void USBD_CDC0_ACM_SendData (int32_t len) {
  // Add code for handling new data send
	int32_t cnt;
	
	cnt = USBD_CDC_ACM_WriteData(0, mantTxBuf, len);
		
	if(cnt<0) {}
		//error	
}

where 

mantTxBuf

is my pointer to the transmitter buffer. I am sharing the same buffer with UART and USB, because my intention is that when I use the USB, the UART will be disable and viceversa.

How "USBD_CDCn_ACM_SendData" works?

Should I implement the asynchronous function to send data ("USBD_CDC_ACM_WriteData") as a independent function?

Is there another strategy to send data when I have characters in my Tx buff ("mantTxBuff")??

Thank you very much!

Hi again Andy,

I have been improving my code, and I am now at the point that I am able to receive characters from the host (PC). My problem now is that I don't understand how the function "USBD_CDCn_ACM_SendData" works.

My purpose is to include the function "USBD_CDC_ACM_WriteData" inside "SendData" function. I know that WriteData is an asynchronous function, but it never interrupts the program.

My code is:

// Called when when all data was sent.
void USBD_CDC0_ACM_SendData (int32_t len) {
  // Add code for handling new data send
	int32_t cnt;
	
	cnt = USBD_CDC_ACM_WriteData(0, mantTxBuf, len);
		
	if(cnt<0) {}
		//error	
}

where 

mantTxBuf

is my pointer to the transmitter buffer. I am sharing the same buffer with UART and USB, because my intention is that when I use the USB, the UART will be disable and viceversa.

How "USBD_CDCn_ACM_SendData" works?

Should I implement the asynchronous function to send data ("USBD_CDC_ACM_WriteData") as a independent function?

Is there another strategy to send data when I have characters in my Tx buff ("mantTxBuff")??

Thank you very much!

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