Minor documentation enhancements.

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

diff --git a/Projects/USBtoSerial/USBtoSerial.c b/Projects/USBtoSerial/USBtoSerial.c
index dd9a133..845c2a5 100644 (file)
--- a/Projects/USBtoSerial/USBtoSerial.c
+++ b/Projects/USBtoSerial/USBtoSerial.c
@@ -73,8 +73,8 @@ int main(void)
 {
        SetupHardware();
        
-       Buffer_Initialize(&USBtoUSART_Buffer);
-       Buffer_Initialize(&USARTtoUSB_Buffer);
+       RingBuffer_InitBuffer(&USBtoUSART_Buffer);
+       RingBuffer_InitBuffer(&USARTtoUSB_Buffer);
 
        LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
        sei();
@@ -82,21 +82,24 @@ int main(void)
        for (;;)
        {
                /* Read bytes from the USB OUT endpoint into the USART transmit buffer */
-               for (uint8_t DataBytesRem = CDC_Device_BytesReceived(&VirtualSerial_CDC_Interface); DataBytesRem != 0; DataBytesRem--)
+               int16_t ReceivedByte = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
+               if (!(ReceivedByte < 0) && !(RingBuffer_IsFull(&USBtoUSART_Buffer)))
+                 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))
                {
-                       if (!(BUFF_STATICSIZE - USBtoUSART_Buffer.Elements))
-                         break;
-                         
-                       Buffer_StoreElement(&USBtoUSART_Buffer, CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface));
+                       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));
                }
                
-               /* Read bytes from the USART receive buffer into the USB IN endpoint */
-               while (USARTtoUSB_Buffer.Elements)
-                 CDC_Device_SendByte(&VirtualSerial_CDC_Interface, Buffer_GetElement(&USARTtoUSB_Buffer));
-               
-               /* Load bytes from the USART transmit buffer into the USART */
-               while (USBtoUSART_Buffer.Elements)
-                 Serial_TxByte(Buffer_GetElement(&USBtoUSART_Buffer));
+               /* Load the next byte from the USART transmit buffer into the USART */
+               if (!(RingBuffer_IsEmpty(&USBtoUSART_Buffer)))
+                 Serial_TxByte(RingBuffer_Remove(&USBtoUSART_Buffer));
                
                CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
                USB_USBTask();
@@ -114,9 +117,11 @@ void SetupHardware(void)
        clock_prescale_set(clock_div_1);
 
        /* Hardware Initialization */
-       Serial_Init(9600, false);
        LEDs_Init();
        USB_Init();
+
+       /* Start the flush timer so that overflows occur rapidly to push received bytes to the USB interface */
+       TCCR0B = (1 << CS02);
 }
 
 /** Event handler for the library USB Connection event. */
@@ -134,10 +139,11 @@ void EVENT_USB_Device_Disconnect(void)
 /** Event handler for the library USB Configuration Changed event. */
 void EVENT_USB_Device_ConfigurationChanged(void)
 {
-       LEDs_SetAllLEDs(LEDMASK_USB_READY);
+       bool ConfigSuccess = true;
+
+       ConfigSuccess &= CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface);
 
-       if (!(CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface)))
-         LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+       LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 }
 
 /** Event handler for the library USB Unhandled Control Request event. */
@@ -154,7 +160,7 @@ ISR(USART1_RX_vect, ISR_BLOCK)
        uint8_t ReceivedByte = UDR1;
 
        if (USB_DeviceState == DEVICE_STATE_Configured)
-         Buffer_StoreElement(&USARTtoUSB_Buffer, ReceivedByte);
+         RingBuffer_Insert(&USARTtoUSB_Buffer, ReceivedByte);
 }
 
 /** Event handler for the CDC Class driver Line Encoding Changed event.
@@ -190,9 +196,17 @@ void EVENT_CDC_Device_LineEncodingChanged(USB_ClassInfo_CDC_Device_t* const CDCI
                        ConfigMask |= ((1 << UCSZ11) | (1 << UCSZ10));
                        break;
        }
+
+       /* Must turn off USART before reconfiguring it, otherwise incorrect operation may occur */
+       UCSR1B = 0;
+       UCSR1A = 0;
+       UCSR1C = 0;
+
+       /* Set the new baud rate before configuring the USART */
+       UBRR1  = SERIAL_2X_UBBRVAL(CDCInterfaceInfo->State.LineEncoding.BaudRateBPS);
        
-       UCSR1A = (1 << U2X1);   
+       /* Reconfigure the USART in double speed mode for a wider baud rate range at the expense of accuracy */
+       UCSR1C = ConfigMask;
+       UCSR1A = (1 << U2X1);
        UCSR1B = ((1 << RXCIE1) | (1 << TXEN1) | (1 << RXEN1));
-       UCSR1C = ConfigMask;    
-       UBRR1  = SERIAL_2X_UBBRVAL(CDCInterfaceInfo->State.LineEncoding.BaudRateBPS);
 }