X-Git-Url: http://git.linex4red.de/pub/USBasp.git/blobdiff_plain/cb779e3d7d32d7c43e0a45bb526de0a04135b0c7..a8b66f318dda3cc18dfcedaa3af3d01ab68b82e8:/Projects/USBtoSerial/USBtoSerial.c

diff --git a/Projects/USBtoSerial/USBtoSerial.c b/Projects/USBtoSerial/USBtoSerial.c
index 3f06acde9..e775541fd 100644
--- a/Projects/USBtoSerial/USBtoSerial.c
+++ b/Projects/USBtoSerial/USBtoSerial.c
@@ -31,7 +31,7 @@
 /** \file
  *
  *  Main source file for the USBtoSerial project. This file contains the main tasks of
- *  the demo and is responsible for the initial application hardware configuration.
+ *  the project and is responsible for the initial application hardware configuration.
  */
 
 #include "USBtoSerial.h"
@@ -39,9 +39,16 @@
 /** Circular buffer to hold data from the host before it is sent to the device via the serial port. */
 RingBuff_t USBtoUSART_Buffer;
 
+/** Underlying data buffer for \ref USBtoUSART_Buffer, where the stored bytes are located. */
+uint8_t    USBtoUSART_Buffer_Data[128];
+
 /** Circular buffer to hold data from the serial port before it is sent to the host. */
 RingBuff_t USARTtoUSB_Buffer;
 
+/** Underlying data buffer for \ref USARTtoUSB_Buffer, where the stored bytes are located. */
+uint8_t    USARTtoUSB_Buffer_Data[128];
+
+
 /** LUFA CDC Class driver interface configuration and state information. This structure is
  *  passed to all CDC Class driver functions, so that multiple instances of the same class
  *  within a device can be differentiated from one another.
@@ -73,28 +80,44 @@ int main(void)
 {
 	SetupHardware();
 
-	RingBuffer_InitBuffer(&USBtoUSART_Buffer);
-	RingBuffer_InitBuffer(&USARTtoUSB_Buffer);
+	RingBuffer_InitBuffer(&USBtoUSART_Buffer, USBtoUSART_Buffer_Data, sizeof(USBtoUSART_Buffer_Data));
+	RingBuffer_InitBuffer(&USARTtoUSB_Buffer, USARTtoUSB_Buffer_Data, sizeof(USARTtoUSB_Buffer_Data));
 
 	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 	sei();
 
 	for (;;)
 	{
-		/* Read bytes from the USB OUT endpoint into the USART transmit buffer */
-		int16_t ReceivedByte = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
-		if (!(ReceivedByte < 0) && !(RingBuffer_IsFull(&USBtoUSART_Buffer)))
-		  RingBuffer_Insert(&USBtoUSART_Buffer, ReceivedByte);
+		/* Only try to read in bytes from the CDC interface if the transmit buffer is not full */
+		if (!(RingBuffer_IsFull(&USBtoUSART_Buffer)))
+		{
+			int16_t ReceivedByte = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
 
+			/* Read bytes from the USB OUT endpoint into the USART transmit buffer */
+			if (!(ReceivedByte < 0))
+			  RingBuffer_Insert(&USBtoUSART_Buffer, ReceivedByte);
+		}
+		
 		/* Check if the UART receive buffer flush timer has expired or the buffer is nearly full */
-		RingBuff_Count_t BufferCount = RingBuffer_GetCount(&USARTtoUSB_Buffer);
+		uint16_t BufferCount = RingBuffer_GetCount(&USARTtoUSB_Buffer);
 		if ((TIFR0 & (1 << TOV0)) || (BufferCount > 200))
 		{
+			/* Clear flush timer expiry flag */
 			TIFR0 |= (1 << TOV0);
 
 			/* Read bytes from the USART receive buffer into the USB IN endpoint */
 			while (BufferCount--)
-			  CDC_Device_SendByte(&VirtualSerial_CDC_Interface, RingBuffer_Remove(&USARTtoUSB_Buffer));
+			{
+				/* Try to send the next byte of data to the host, abort if there is an error without dequeuing */
+				if (CDC_Device_SendByte(&VirtualSerial_CDC_Interface,
+				                        RingBuffer_Peek(&USARTtoUSB_Buffer)) != ENDPOINT_READYWAIT_NoError)
+				{
+					break;
+				}
+
+				/* Dequeue the already sent byte from the buffer now we have confirmed that no transmission error occurred */
+				RingBuffer_Remove(&USARTtoUSB_Buffer);
+			}
 		}
 
 		/* Load the next byte from the USART transmit buffer into the USART */
@@ -146,8 +169,8 @@ void EVENT_USB_Device_ConfigurationChanged(void)
 	LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 }
 
-/** Event handler for the library USB Unhandled Control Request event. */
-void EVENT_USB_Device_UnhandledControlRequest(void)
+/** Event handler for the library USB Control Request reception event. */
+void EVENT_USB_Device_ControlRequest(void)
 {
 	CDC_Device_ProcessControlRequest(&VirtualSerial_CDC_Interface);
 }