Fixed USBtoSerial and XPLAINBridge demos discarding data from the PC if the send...

[pub/USBasp.git] / Projects / USBtoSerial / USBtoSerial.c

diff --git a/Projects/USBtoSerial/USBtoSerial.c b/Projects/USBtoSerial/USBtoSerial.c
index 3f06acd..c26667d 100644 (file)
--- a/Projects/USBtoSerial/USBtoSerial.c
+++ b/Projects/USBtoSerial/USBtoSerial.c
@@ -81,15 +81,21 @@ int main(void)
 
        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);
                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 */