Demo/PIC24_MPLAB/serial/serial.c - third_party/github/FreeRTOS/FreeRTOS-Kernel - Git at Google

 /*
     FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

     ***************************************************************************
     *                                                                         *
     * If you are:                                                             *
     *                                                                         *
     *    + New to FreeRTOS,                                                   *
     *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
     *    + Looking for basic training,                                        *
     *    + Wanting to improve your FreeRTOS skills and productivity           *
     *                                                                         *
     * then take a look at the FreeRTOS eBook                                  *
     *                                                                         *
     *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
     *                  http://www.FreeRTOS.org/Documentation                  *
     *                                                                         *
     * A pdf reference manual is also available.  Both are usually delivered   *
     * to your inbox within 20 minutes to two hours when purchased between 8am *
     * and 8pm GMT (although please allow up to 24 hours in case of            *
     * exceptional circumstances).  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 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.

     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.

 NOTE:  This driver is primarily to test the scheduler functionality.  It does
 not effectively use the buffers or DMA and is therefore not intended to be
 an example of an efficient driver. */

 /* Standard include file. */
 #include <stdlib.h>

 /* Scheduler include files. */
 #include "FreeRTOS.h"
 #include "queue.h"
 #include "task.h"

 /* Demo app include files. */
 #include "serial.h"

 /* Hardware setup. */
 #define serOUTPUT						0
 #define serINPUT						1
 #define serLOW_SPEED					0
 #define serONE_STOP_BIT					0
 #define serEIGHT_DATA_BITS_NO_PARITY	0
 #define serNORMAL_IDLE_STATE			0
 #define serAUTO_BAUD_OFF				0
 #define serLOOPBACK_OFF					0
 #define serWAKE_UP_DISABLE				0
 #define serNO_HARDWARE_FLOW_CONTROL		0
 #define serSTANDARD_IO					0
 #define serNO_IRDA						0
 #define serCONTINUE_IN_IDLE_MODE		0
 #define serUART_ENABLED					1
 #define serINTERRUPT_ON_SINGLE_CHAR		0
 #define serTX_ENABLE					1
 #define serINTERRUPT_ENABLE				1
 #define serINTERRUPT_DISABLE			0
 #define serCLEAR_FLAG					0
 #define serSET_FLAG						1


 /* The queues used to communicate between tasks and ISR's. */
 static xQueueHandle xRxedChars;
 static xQueueHandle xCharsForTx;

 static portBASE_TYPE xTxHasEnded;
 /*-----------------------------------------------------------*/

 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
 {
 char cChar;

 	/* 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 ) );

 	/* Setup the UART. */
 	U2MODEbits.BRGH		= serLOW_SPEED;
 	U2MODEbits.STSEL	= serONE_STOP_BIT;
 	U2MODEbits.PDSEL	= serEIGHT_DATA_BITS_NO_PARITY;
 	U2MODEbits.RXINV	= serNORMAL_IDLE_STATE;
 	U2MODEbits.ABAUD	= serAUTO_BAUD_OFF;
 	U2MODEbits.LPBACK	= serLOOPBACK_OFF;
 	U2MODEbits.WAKE		= serWAKE_UP_DISABLE;
 	U2MODEbits.UEN		= serNO_HARDWARE_FLOW_CONTROL;
 	U2MODEbits.IREN		= serNO_IRDA;
 	U2MODEbits.USIDL	= serCONTINUE_IN_IDLE_MODE;
 	U2MODEbits.UARTEN	= serUART_ENABLED;

 	U2BRG = (unsigned short)(( (float)configCPU_CLOCK_HZ / ( (float)16 * (float)ulWantedBaud ) ) - (float)0.5);

 	U2STAbits.URXISEL	= serINTERRUPT_ON_SINGLE_CHAR;
 	U2STAbits.UTXEN		= serTX_ENABLE;
 	U2STAbits.UTXINV	= serNORMAL_IDLE_STATE;
 	U2STAbits.UTXISEL0	= serINTERRUPT_ON_SINGLE_CHAR;
 	U2STAbits.UTXISEL1	= serINTERRUPT_ON_SINGLE_CHAR;

 	/* It is assumed that this function is called prior to the scheduler being
 	started.  Therefore interrupts must not be allowed to occur yet as they
 	may attempt to perform a context switch. */
 	portDISABLE_INTERRUPTS();

 	IFS1bits.U2RXIF = serCLEAR_FLAG;
 	IFS1bits.U2TXIF = serCLEAR_FLAG;
 	IPC7bits.U2RXIP = configKERNEL_INTERRUPT_PRIORITY;
 	IPC7bits.U2TXIP = configKERNEL_INTERRUPT_PRIORITY;
 	IEC1bits.U2TXIE = serINTERRUPT_ENABLE;
 	IEC1bits.U2RXIE = serINTERRUPT_ENABLE;

 	/* Clear the Rx buffer. */
 	while( U2STAbits.URXDA == serSET_FLAG )
 	{
 		cChar = U2RXREG;
 	}

 	xTxHasEnded = pdTRUE;

 	return NULL;
 }
 /*-----------------------------------------------------------*/

 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
 {
 	/* Only one port is supported. */
 	( 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;
 	}
 }
 /*-----------------------------------------------------------*/

 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
 {
 	/* Only one port is supported. */
 	( void ) pxPort;

 	/* Return false if after the block time there is no room on the Tx queue. */
 	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
 	{
 		return pdFAIL;
 	}

 	/* A critical section should not be required as xTxHasEnded will not be
 	written to by the ISR if it is already 0 (is this correct?). */
 	if( xTxHasEnded )
 	{
 		xTxHasEnded = pdFALSE;
 		IFS1bits.U2TXIF = serSET_FLAG;
 	}

 	return pdPASS;
 }
 /*-----------------------------------------------------------*/

 void vSerialClose( xComPortHandle xPort )
 {
 }
 /*-----------------------------------------------------------*/

 void __attribute__((__interrupt__, auto_psv)) _U2RXInterrupt( void )
 {
 char cChar;
 portBASE_TYPE 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. */
 	IFS1bits.U2RXIF = serCLEAR_FLAG;
 	while( U2STAbits.URXDA )
 	{
 		cChar = U2RXREG;
 		xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
 	}

 	if( xHigherPriorityTaskWoken != pdFALSE )
 	{
 		taskYIELD();
 	}
 }
 /*-----------------------------------------------------------*/

 void __attribute__((__interrupt__, auto_psv)) _U2TXInterrupt( void )
 {
 signed char cChar;
 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

 	/* If the transmit buffer is full we cannot get the next character.
 	Another interrupt will occur the next time there is space so this does
 	not matter. */
 	IFS1bits.U2TXIF = serCLEAR_FLAG;
 	while( !( U2STAbits.UTXBF ) )
 	{
 		if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
 		{
 			/* Send the next character queued for Tx. */
 			U2TXREG = cChar;
 		}
 		else
 		{
 			/* Queue empty, nothing to send. */
 			xTxHasEnded = pdTRUE;
 			break;
 		}
 	}

 	if( xHigherPriorityTaskWoken != pdFALSE )
 	{
 		taskYIELD();
 	}
 }
	/*
	FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

	***************************************************************************
	* *
	* If you are: *
	* *
	* + New to FreeRTOS, *
	* + Wanting to learn FreeRTOS or multitasking in general quickly *
	* + Looking for basic training, *
	* + Wanting to improve your FreeRTOS skills and productivity *
	* *
	* then take a look at the FreeRTOS eBook *
	* *
	* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
	* http://www.FreeRTOS.org/Documentation *
	* *
	* A pdf reference manual is also available. Both are usually delivered *
	* to your inbox within 20 minutes to two hours when purchased between 8am *
	* and 8pm GMT (although please allow up to 24 hours in case of *
	* exceptional circumstances). 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 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.

	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.

	NOTE: This driver is primarily to test the scheduler functionality. It does
	not effectively use the buffers or DMA and is therefore not intended to be
	an example of an efficient driver. */

	/* Standard include file. */
	#include <stdlib.h>

	/* Scheduler include files. */
	#include "FreeRTOS.h"
	#include "queue.h"
	#include "task.h"

	/* Demo app include files. */
	#include "serial.h"

	/* Hardware setup. */
	#define serOUTPUT 0
	#define serINPUT 1
	#define serLOW_SPEED 0
	#define serONE_STOP_BIT 0
	#define serEIGHT_DATA_BITS_NO_PARITY 0
	#define serNORMAL_IDLE_STATE 0
	#define serAUTO_BAUD_OFF 0
	#define serLOOPBACK_OFF 0
	#define serWAKE_UP_DISABLE 0
	#define serNO_HARDWARE_FLOW_CONTROL 0
	#define serSTANDARD_IO 0
	#define serNO_IRDA 0
	#define serCONTINUE_IN_IDLE_MODE 0
	#define serUART_ENABLED 1
	#define serINTERRUPT_ON_SINGLE_CHAR 0
	#define serTX_ENABLE 1
	#define serINTERRUPT_ENABLE 1
	#define serINTERRUPT_DISABLE 0
	#define serCLEAR_FLAG 0
	#define serSET_FLAG 1


	/* The queues used to communicate between tasks and ISR's. */
	static xQueueHandle xRxedChars;
	static xQueueHandle xCharsForTx;

	static portBASE_TYPE xTxHasEnded;
	/-----------------------------------------------------------/

	xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
	{
	char cChar;

	/* 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 ) );

	/* Setup the UART. */
	U2MODEbits.BRGH = serLOW_SPEED;
	U2MODEbits.STSEL = serONE_STOP_BIT;
	U2MODEbits.PDSEL = serEIGHT_DATA_BITS_NO_PARITY;
	U2MODEbits.RXINV = serNORMAL_IDLE_STATE;
	U2MODEbits.ABAUD = serAUTO_BAUD_OFF;
	U2MODEbits.LPBACK = serLOOPBACK_OFF;
	U2MODEbits.WAKE = serWAKE_UP_DISABLE;
	U2MODEbits.UEN = serNO_HARDWARE_FLOW_CONTROL;
	U2MODEbits.IREN = serNO_IRDA;
	U2MODEbits.USIDL = serCONTINUE_IN_IDLE_MODE;
	U2MODEbits.UARTEN = serUART_ENABLED;

	U2BRG = (unsigned short)(( (float)configCPU_CLOCK_HZ / ( (float)16 * (float)ulWantedBaud ) ) - (float)0.5);

	U2STAbits.URXISEL = serINTERRUPT_ON_SINGLE_CHAR;
	U2STAbits.UTXEN = serTX_ENABLE;
	U2STAbits.UTXINV = serNORMAL_IDLE_STATE;
	U2STAbits.UTXISEL0 = serINTERRUPT_ON_SINGLE_CHAR;
	U2STAbits.UTXISEL1 = serINTERRUPT_ON_SINGLE_CHAR;

	/* It is assumed that this function is called prior to the scheduler being
	started. Therefore interrupts must not be allowed to occur yet as they
	may attempt to perform a context switch. */
	portDISABLE_INTERRUPTS();

	IFS1bits.U2RXIF = serCLEAR_FLAG;
	IFS1bits.U2TXIF = serCLEAR_FLAG;
	IPC7bits.U2RXIP = configKERNEL_INTERRUPT_PRIORITY;
	IPC7bits.U2TXIP = configKERNEL_INTERRUPT_PRIORITY;
	IEC1bits.U2TXIE = serINTERRUPT_ENABLE;
	IEC1bits.U2RXIE = serINTERRUPT_ENABLE;

	/* Clear the Rx buffer. */
	while( U2STAbits.URXDA == serSET_FLAG )
	{
	cChar = U2RXREG;
	}

	xTxHasEnded = pdTRUE;

	return NULL;
	}
	/-----------------------------------------------------------/

	signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
	{
	/* Only one port is supported. */
	( 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;
	}
	}
	/-----------------------------------------------------------/

	signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
	{
	/* Only one port is supported. */
	( void ) pxPort;

	/* Return false if after the block time there is no room on the Tx queue. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
	{
	return pdFAIL;
	}

	/* A critical section should not be required as xTxHasEnded will not be
	written to by the ISR if it is already 0 (is this correct?). */
	if( xTxHasEnded )
	{
	xTxHasEnded = pdFALSE;
	IFS1bits.U2TXIF = serSET_FLAG;
	}

	return pdPASS;
	}
	/-----------------------------------------------------------/

	void vSerialClose( xComPortHandle xPort )
	{
	}
	/-----------------------------------------------------------/

	void __attribute__((__interrupt__, auto_psv)) _U2RXInterrupt( void )
	{
	char cChar;
	portBASE_TYPE 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. */
	IFS1bits.U2RXIF = serCLEAR_FLAG;
	while( U2STAbits.URXDA )
	{
	cChar = U2RXREG;
	xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
	}

	if( xHigherPriorityTaskWoken != pdFALSE )
	{
	taskYIELD();
	}
	}
	/-----------------------------------------------------------/

	void __attribute__((__interrupt__, auto_psv)) _U2TXInterrupt( void )
	{
	signed char cChar;
	portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* If the transmit buffer is full we cannot get the next character.
	Another interrupt will occur the next time there is space so this does
	not matter. */
	IFS1bits.U2TXIF = serCLEAR_FLAG;
	while( !( U2STAbits.UTXBF ) )
	{
	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
	{
	/* Send the next character queued for Tx. */
	U2TXREG = cChar;
	}
	else
	{
	/* Queue empty, nothing to send. */
	xTxHasEnded = pdTRUE;
	break;
	}
	}

	if( xHigherPriorityTaskWoken != pdFALSE )
	{
	taskYIELD();
	}
	}