20100923-V6.1.0-RC2/Demo/ARM9_AT91SAM9XE_IAR/serial/serial.c

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+/*
+    FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
+
+    ***************************************************************************
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+
+    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 exception 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.
+
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+
+    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.
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+*/
+
+/*
+	BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
+*/
+
+/* Standard includes. */
+#include <stdlib.h>
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+#include "queue.h"
+
+/* Demo application includes. */
+#include "serial.h"
+
+/* Atmel library includes. */
+#include <usart/usart.h>
+#include <aic/aic.h>
+#include <pmc/pmc.h>
+
+/*-----------------------------------------------------------*/
+
+/* Location of the COM0 registers. */
+#define serCOM0							( ( AT91PS_USART ) AT91C_BASE_US0 )
+
+/* Interrupt control macros. */
+#define serINTERRUPT_LEVEL				( 5 )
+#define vInterruptOn()					serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
+#define vInterruptOff()					serCOM0->US_IDR = AT91C_US_TXRDY
+
+/* Misc constants. */
+#define serINVALID_QUEUE				( ( xQueueHandle ) 0 )
+#define serHANDLE						( ( xComPortHandle ) 1 )
+#define serNO_BLOCK						( ( portTickType ) 0 )
+#define serNO_TIMEGUARD					( ( unsigned long ) 0 )
+#define serNO_PERIPHERAL_B_SETUP		( ( unsigned long ) 0 )
+
+
+/* Queues used to hold received characters, and characters waiting to be
+transmitted. */
+static xQueueHandle xRxedChars;
+static xQueueHandle xCharsForTx;
+
+/*-----------------------------------------------------------*/
+
+/* The interrupt service routine. */
+__arm void vSerialISR( void );
+
+/*-----------------------------------------------------------*/
+
+/*
+ * See the serial2.h header file.
+ */
+xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
+{
+xComPortHandle xReturn = serHANDLE;
+
+	/* Create the queues used to hold Rx and Tx characters. */
+	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
+	xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
+
+	/* If the queues were created correctly then setup the serial port
+	hardware. */
+	if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
+	{
+		PMC_EnablePeripheral( AT91C_ID_US0 );	
+		portENTER_CRITICAL();
+		{
+			USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
+
+			/* Enable Rx and Tx. */
+			USART_SetTransmitterEnabled( serCOM0, pdTRUE );
+			USART_SetReceiverEnabled( serCOM0, pdTRUE );
+
+			/* Enable the Rx interrupts.  The Tx interrupts are not enabled
+			until there are characters to be transmitted. */
+			serCOM0->US_IER = AT91C_US_RXRDY;
+
+			/* Enable the interrupts in the AIC. */
+			AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
+			AIC_EnableIT( AT91C_ID_US0 );
+		}
+		portEXIT_CRITICAL();
+	}
+	else
+	{
+		xReturn = ( xComPortHandle ) 0;
+	}
+
+	/* This demo file only supports a single port but we have to return
+	something to comply with the standard demo header file. */
+	return xReturn;
+}
+/*-----------------------------------------------------------*/
+
+signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
+{
+	/* The port handle is not required as this driver only supports one port. */
+	( void ) pxPort;
+
+	/* 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;
+	}
+}
+/*-----------------------------------------------------------*/
+
+void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
+{
+signed char *pxNext;
+
+	/* A couple of parameters that this port does not use. */
+	( void ) usStringLength;
+	( void ) pxPort;
+
+	/* NOTE: This implementation does not handle the queue being full as no
+	block time is used! */
+
+	/* The port handle is not required as this driver only supports UART0. */
+	( void ) pxPort;
+
+	/* Send each character in the string, one at a time. */
+	pxNext = ( signed char * ) pcString;
+	while( *pxNext )
+	{
+		xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
+		pxNext++;
+	}
+}
+/*-----------------------------------------------------------*/
+
+signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
+{
+	/* Just to remove compiler warning. */
+	( void ) pxPort;
+	
+	/* Place the character in the queue of characters to be transmitted. */
+	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
+	{
+		return pdFAIL;
+	}
+
+	/* Turn on the Tx interrupt so the ISR will remove the character from the
+	queue and send it.   This does not need to be in a critical section as
+	if the interrupt has already removed the character the next interrupt
+	will simply turn off the Tx interrupt again. */
+	vInterruptOn();
+
+	return pdPASS;
+}
+/*-----------------------------------------------------------*/
+
+void vSerialClose( xComPortHandle xPort )
+{
+	/* Not supported as not required by the demo application. */
+	( void ) xPort;
+}
+/*-----------------------------------------------------------*/
+
+/* Serial port ISR.  This can cause a context switch so is not defined as a
+standard ISR using the __irq keyword.  Instead a wrapper function is defined
+within serialISR.s79 which in turn calls this function.  See the port
+documentation on the FreeRTOS.org website for more information. */
+__arm void vSerialISR( void )
+{
+unsigned long ulStatus;
+signed char cChar;
+portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
+
+	/* What caused the interrupt? */
+	ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
+
+	if( ulStatus & AT91C_US_TXRDY )
+	{
+		/* The interrupt was caused by the THR becoming empty.  Are there any
+		more characters to transmit? */
+		if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
+		{
+			/* A character was retrieved from the queue so can be sent to the
+			THR now. */
+			serCOM0->US_THR = cChar;
+		}
+		else
+		{
+			/* Queue empty, nothing to send so turn off the Tx interrupt. */
+			vInterruptOff();
+		}		
+	}
+
+	if( ulStatus & AT91C_US_RXRDY )
+	{
+		/* The interrupt was caused by a character being received.  Grab the
+		character from the RHR and place it in the queue or received
+		characters. */
+		cChar = serCOM0->US_RHR;
+		xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
+	}
+
+	/* If a task was woken by either a character being received or a character
+	being transmitted then we may need to switch to another task. */
+	portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
+
+	/* End the interrupt in the AIC. */
+	AT91C_BASE_AIC->AIC_EOICR = 0;
+}
+
+
+
+
+