Fixed CDC and USBtoSerial demos freezing where buffers were full while still...

Fixed CDC and USBtoSerial demos freezing where buffers were full while still transmitting or receiving (thanks to Peter Hand).

Demos/Device/CDC/CDC.c

@@ -300,14 +300,22 @@ TASK(CDC_Task)
 		/* Write the String to the Endpoint */
 		Endpoint_Write_Stream_LE(ReportString, strlen(ReportString));
 		
+		/* Remember if the packet to send completely fills the endpoint */
+		bool IsFull = (Endpoint_BytesInEndpoint() == CDC_TXRX_EPSIZE);
+
 		/* Finalize the stream transfer to send the last packet */
 		Endpoint_ClearIN();
 
-		/* Wait until the endpoint is ready for another packet */
-		while (!(Endpoint_IsINReady()));
-		
-		/* Send an empty packet to ensure that the host does not buffer data sent to it */
-		Endpoint_ClearIN();
+		/* If the last packet filled the endpoint, send an empty packet to release the buffer on 
+		 * the receiver (otherwise all data will be cached until a non-full packet is received) */
+		if (IsFull)
+		{
+			/* Wait until the endpoint is ready for another packet */
+			while (!(Endpoint_IsINReady()));
+			
+			/* Send an empty packet to ensure that the host does not buffer data sent to it */
+			Endpoint_ClearIN();
+		}
 	}
 
 	/* Select the Serial Rx Endpoint */

Demos/Device/USBtoSerial/USBtoSerial.c

@@ -246,18 +246,19 @@ TASK(CDC_Task)
 		
 		if (Endpoint_IsOUTReceived())
 		{
-			/* Read the received data endpoint into the transmission buffer */
-			while (Endpoint_BytesInEndpoint())
+			/* Read the bytes in from the endpoint into the buffer while space is available */
+			while (Endpoint_BytesInEndpoint() && (BUFF_STATICSIZE - Rx_Buffer.Elements))
 			{
-				/* Wait until the buffer has space for a new character */
-				while (!((BUFF_STATICSIZE - Rx_Buffer.Elements)));
-			
 				/* Store each character from the endpoint */
 				Buffer_StoreElement(&Rx_Buffer, Endpoint_Read_Byte());
 			}
 			
-			/* Clear the endpoint buffer */
-			Endpoint_ClearOUT();
+			/* Check to see if all bytes in the current packet have been read */
+			if (!(Endpoint_BytesInEndpoint()))
+			{
+				/* Clear the endpoint buffer */
+				Endpoint_ClearOUT();
+			}
 		}
 		
 		/* Check if Rx buffer contains data */
@@ -280,18 +281,29 @@ TASK(CDC_Task)
 			/* Wait until Serial Tx Endpoint Ready for Read/Write */
 			while (!(Endpoint_IsReadWriteAllowed()));
 			
-			/* Write the transmission buffer contents to the received data endpoint */
+			/* Write the bytes from the buffer to the endpoint while space is available */
 			while (Tx_Buffer.Elements && (Endpoint_BytesInEndpoint() < CDC_TXRX_EPSIZE))
-			  Endpoint_Write_Byte(Buffer_GetElement(&Tx_Buffer));
+			{
+				/* Write each byte retreived from the buffer to the endpoint */
+				Endpoint_Write_Byte(Buffer_GetElement(&Tx_Buffer));
+			}
+			
+			/* Remember if the packet to send completely fills the endpoint */
+			bool IsFull = (Endpoint_BytesInEndpoint() == CDC_TXRX_EPSIZE);
 			
 			/* Send the data */
 			Endpoint_ClearIN();
 
-			/* Wait until Serial Tx Endpoint Ready for Read/Write */
-			while (!(Endpoint_IsReadWriteAllowed()));
+			/* If no more data to send and the last packet filled the endpoint, send an empty packet to release
+			 * the buffer on the receiver (otherwise all data will be cached until a non-full packet is received) */
+			if (IsFull && !(Tx_Buffer.Elements))
+			{
+				/* Wait until Serial Tx Endpoint Ready for Read/Write */
+				while (!(Endpoint_IsReadWriteAllowed()));
 
-			/* Send an empty packet to terminate the transfer */
-			Endpoint_ClearIN();
+				/* Send an empty packet to terminate the transfer */
+				Endpoint_ClearIN();
+			}
 		}
 	}
 }

LUFA/ChangeLog.txt

@@ -48,6 +48,7 @@
   *  - Removed old endpoint and pipe aliased read/write/discard routines which did not have an explicit endian specifier for clarity
   *  - Removed the ButtLoadTag.h header file, as no one used for its intended purpose anyway
   *  - Renamed the main Drivers/AT90USBXXX directory to Drivers/Peripheral, renamed the Serial_Stream driver to SerialStream
+  *  - Fixed CDC and USBtoSerial demos freezing where buffers were full while still transmitting or receiving (thanks to Peter Hand)
   *    
   *
   *  \section Sec_ChangeLog090401 Version 090401