20120401V7.1.1-RC1/Demo/AVR_ATMega323_IAR/serial/serial.c

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+/*
+    FreeRTOS V7.1.0 - Copyright (C) 2011 Real Time Engineers Ltd.
+	
+
+    ***************************************************************************
+     *                                                                       *
+     *    FreeRTOS tutorial books are available in pdf and paperback.        *
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+     *    available.                                                         *
+     *                                                                       *
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+     *    ensuring you get running as quickly as possible and with an        *
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+     *    the FreeRTOS project to continue with its mission of providing     *
+     *    professional grade, cross platform, de facto standard solutions    *
+     *    for microcontrollers - completely free of charge!                  *
+     *                                                                       *
+     *    >>> See http://www.FreeRTOS.org/Documentation for details. <<<     *
+     *                                                                       *
+     *    Thank you for using FreeRTOS, and thank you for your support!      *
+     *                                                                       *
+    ***************************************************************************
+
+
+    This file is part of the FreeRTOS distribution.
+
+    FreeRTOS is free software; you can redistribute it and/or modify it under
+    the terms of the GNU General Public License (version 2) as published by the
+    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
+    >>>NOTE<<< The modification to the GPL is included to allow you to
+    distribute a combined work that includes FreeRTOS without being obliged to
+    provide the source code for proprietary components outside of the FreeRTOS
+    kernel.  FreeRTOS is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+    more details. You should have received a copy of the GNU General Public
+    License and the FreeRTOS license exception along with FreeRTOS; if not it
+    can be viewed here: http://www.freertos.org/a00114.html and also obtained
+    by writing to Richard Barry, contact details for whom are available on the
+    FreeRTOS WEB site.
+
+    1 tab == 4 spaces!
+
+    http://www.FreeRTOS.org - Documentation, latest information, license and
+    contact details.
+
+    http://www.SafeRTOS.com - A version that is certified for use in safety
+    critical systems.
+
+    http://www.OpenRTOS.com - Commercial support, development, porting,
+    licensing and training services.
+*/
+
+
+/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR IAR AVR PORT. */
+
+
+#include <stdlib.h>
+#include "FreeRTOS.h"
+#include "queue.h"
+#include "task.h"
+#include "serial.h"
+
+#define serBAUD_DIV_CONSTANT			( ( unsigned long ) 16 )
+
+/* Constants for writing to UCSRB. */
+#define serRX_INT_ENABLE				( ( unsigned char ) 0x80 )
+#define serRX_ENABLE					( ( unsigned char ) 0x10 )
+#define serTX_ENABLE					( ( unsigned char ) 0x08 )
+#define serTX_INT_ENABLE				( ( unsigned char ) 0x20 )
+
+/* Constants for writing to UCSRC. */
+#define serUCSRC_SELECT					( ( unsigned char ) 0x80 )
+#define serEIGHT_DATA_BITS				( ( unsigned char ) 0x06 )
+
+static xQueueHandle xRxedChars;
+static xQueueHandle xCharsForTx;
+
+#define vInterruptOn()										\
+{															\
+	unsigned char ucByte;								\
+															\
+	ucByte = UCSRB;											\
+	ucByte |= serTX_INT_ENABLE;								\
+	outb( UCSRB, ucByte );									\
+}																				
+/*-----------------------------------------------------------*/
+
+#define vInterruptOff()										\
+{															\
+	unsigned char ucByte;								\
+															\
+	ucByte = UCSRB;											\
+	ucByte &= ~serTX_INT_ENABLE;							\
+	outb( UCSRB, ucByte );									\
+}
+/*-----------------------------------------------------------*/
+
+xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
+{
+unsigned long ulBaudRateCounter;
+unsigned char ucByte;
+
+	portENTER_CRITICAL();
+	{
+		/* Create the queues used by the com test task. */
+		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
+		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
+
+		/* Calculate the baud rate register value from the equation in the
+		data sheet. */
+		ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;
+
+		/* Set the baud rate. */	
+		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
+		outb( UBRRL, ucByte );
+
+		ulBaudRateCounter >>= ( unsigned long ) 8;
+		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
+		outb( UBRRH, ucByte );
+
+		/* Enable the Rx interrupt.  The Tx interrupt will get enabled
+		later. Also enable the Rx and Tx. */
+		outb( UCSRB, serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );
+
+		/* Set the data bits to 8. */
+		outb( UCSRC, serUCSRC_SELECT | serEIGHT_DATA_BITS );
+	}
+	portEXIT_CRITICAL();
+	
+	/* Unlike other ports, this serial code does not allow for more than one
+	com port.  We therefore don't return a pointer to a port structure and can
+	instead just return NULL. */
+	return NULL;
+}
+/*-----------------------------------------------------------*/
+
+signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
+{
+	/* Get the next character from the buffer.  Return false if no characters
+	are available, or arrive before xBlockTime expires. */
+	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
+	{
+		return pdTRUE;
+	}
+	else
+	{
+		return pdFALSE;
+	}
+}
+/*-----------------------------------------------------------*/
+
+signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
+{
+	/* Return false if after the block time there is no room on the Tx queue. */
+	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
+	{
+		return pdFAIL;
+	}
+
+	vInterruptOn();
+
+	return pdPASS;
+}
+/*-----------------------------------------------------------*/
+
+void vSerialClose( xComPortHandle xPort )
+{
+unsigned char ucByte;
+
+	/* Turn off the interrupts.  We may also want to delete the queues and/or
+	re-install the original ISR. */
+
+	portENTER_CRITICAL();
+	{
+		vInterruptOff();
+		ucByte = UCSRB;
+		ucByte &= ~serRX_INT_ENABLE;
+		outb( UCSRB, ucByte );
+	}
+	portEXIT_CRITICAL();
+}
+/*-----------------------------------------------------------*/
+
+__interrupt void SIG_UART_RECV( void )
+{
+signed char ucChar, xHigherPriorityTaskWoken = pdFALSE;
+
+	/* Get the character and post it on the queue of Rxed characters.
+	If the post causes a task to wake force a context switch as the woken task
+	may have a higher priority than the task we have interrupted. */
+	ucChar = UDR;
+
+	xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );
+
+	if( xHigherPriorityTaskWoken != pdFALSE )
+	{
+		taskYIELD();
+	}
+}
+/*-----------------------------------------------------------*/
+
+__interrupt void SIG_UART_DATA( void )
+{
+signed char cChar, cTaskWoken = pdFALSE;
+
+	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
+	{
+		/* Send the next character queued for Tx. */
+		outb( UDR, cChar );
+	}
+	else
+	{
+		/* Queue empty, nothing to send. */
+		vInterruptOff();
+	}
+}
+