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211 lines
7.9 KiB
C
211 lines
7.9 KiB
C
/*
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FreeRTOS V7.0.2 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* FreeRTOS tutorial books are available in pdf and paperback. *
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* Complete, revised, and edited pdf reference manuals are also *
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* available. *
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* *
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* Purchasing FreeRTOS documentation will not only help you, by *
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* ensuring you get running as quickly as possible and with an *
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* in-depth knowledge of how to use FreeRTOS, it will also help *
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* the FreeRTOS project to continue with its mission of providing *
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* professional grade, cross platform, de facto standard solutions *
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* for microcontrollers - completely free of charge! *
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* *
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* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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* *
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* Thank you for using FreeRTOS, and thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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>>>NOTE<<< The modification to the GPL is included to allow you to
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distribute a combined work that includes FreeRTOS without being obliged to
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provide the source code for proprietary components outside of the FreeRTOS
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kernel. FreeRTOS is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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*
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* This is not a proper UART driver. It only supports one port, uses loopback
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* mode, and is used to test interrupts that use the FreeRTOS API as part of
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* a wider test suite. Nor is it intended to show an efficient implementation
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* of a UART interrupt service routine as queues are used to pass individual
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* characters one at a time!
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*/
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/* Standard includes. */
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#include <stdlib.h>
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "queue.h"
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#include "task.h"
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/* Demo application includes. */
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#include "serial.h"
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/* Misc. constants. */
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#define serNO_BLOCK ( ( portTickType ) 0 )
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/* The queue used to hold received characters. */
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static xQueueHandle xRxedChars;
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/* The queue used to hold characters waiting transmission. */
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static xQueueHandle xCharsForTx;
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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{
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unsigned portLONG ulBaudRateCount;
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/* Initialise the hardware. */
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/* Generate the baud rate constants for the wanted baud rate. */
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ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
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portENTER_CRITICAL();
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{
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/* Create the queues used by the com test task. */
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xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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/* Reset UART. */
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UCA1CTL1 |= UCSWRST;
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/* Use SMCLK. */
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UCA1CTL1 = UCSSEL0 | UCSSEL1;
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/* Setup baud rate low byte. */
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UCA1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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/* Setup baud rate high byte. */
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ulBaudRateCount >>= 8UL;
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UCA1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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/* UCLISTEN sets loopback mode! */
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UCA1STAT = UCLISTEN;
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/* Enable interrupts. */
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UCA1IE |= UCRXIE;
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/* Take out of reset. */
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UCA1CTL1 &= ~UCSWRST;
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}
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portEXIT_CRITICAL();
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/* Note the comments at the top of this file about this not being a generic
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UART driver. */
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return NULL;
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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{
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/* Get the next character from the buffer. Return false if no characters
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are available, or arrive before xBlockTime expires. */
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if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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{
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return pdTRUE;
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}
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else
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{
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return pdFALSE;
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}
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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{
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signed portBASE_TYPE xReturn;
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/* Send the next character to the queue of characters waiting transmission,
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then enable the UART Tx interrupt, just in case UART transmission has already
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completed and switched itself off. */
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xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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UCA1IE |= UCTXIE;
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return xReturn;
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}
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/*-----------------------------------------------------------*/
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/* The implementation of this interrupt is provided to demonstrate the use
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of queues from inside an interrupt service routine. It is *not* intended to
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be an efficient interrupt implementation. A real application should make use
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of the DMA. Or, as a minimum, transmission and reception could use a simple
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RAM ring buffer, and synchronise with a task using a semaphore when a complete
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message has been received or transmitted. */
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#pragma vector=USCI_A1_VECTOR
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static __interrupt void prvUSCI_A1_ISR( void )
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{
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signed char cChar;
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portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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while( ( UCA1IFG & UCRXIFG ) != 0 )
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{
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/* Get the character from the UART and post it on the queue of Rxed
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characters. */
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cChar = UCA1RXBUF;
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xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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}
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/* If there is a Tx interrupt pending and the tx interrupts are enabled. */
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if( ( UCA1IFG & UCTXIFG ) != 0 )
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{
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/* The previous character has been transmitted. See if there are any
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further characters waiting transmission. */
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if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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{
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/* There was another character queued - transmit it now. */
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UCA1TXBUF = cChar;
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}
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else
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{
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/* There were no other characters to transmit - disable the Tx
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interrupt. */
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UCA1IE &= ~UCTXIE;
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}
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}
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__bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF );
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/* If writing to a queue caused a task to unblock, and the unblocked task
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has a priority equal to or above the task that this interrupt interrupted,
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then lHigherPriorityTaskWoken will have been set to pdTRUE internally within
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xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this
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interrupt returns directly to the higher priority unblocked task.
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THIS MUST BE THE LAST THING DONE IN THE ISR. */
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portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
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}
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