2 FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 >>>NOTE<<< The modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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55 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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57 * This is not a proper UART driver. It only supports one port, uses loopback
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58 * mode, and is used to test interrupts that use the FreeRTOS API as part of
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59 * a wider test suite. Nor is it intended to show an efficient implementation
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60 * of a UART interrupt service routine as queues are used to pass individual
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61 * characters one at a time!
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64 /* Standard includes. */
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67 /* Scheduler includes. */
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68 #include "FreeRTOS.h"
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72 /* Demo application includes. */
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75 /* Misc. constants. */
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76 #define serNO_BLOCK ( ( portTickType ) 0 )
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78 /* The queue used to hold received characters. */
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79 static xQueueHandle xRxedChars;
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81 /* The queue used to hold characters waiting transmission. */
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82 static xQueueHandle xCharsForTx;
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84 /*-----------------------------------------------------------*/
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86 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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88 unsigned portLONG ulBaudRateCount;
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90 /* Initialise the hardware. */
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92 /* Generate the baud rate constants for the wanted baud rate. */
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93 ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
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95 portENTER_CRITICAL();
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97 /* Create the queues used by the com test task. */
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98 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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99 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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102 UCA1CTL1 |= UCSWRST;
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105 UCA1CTL1 = UCSSEL0 | UCSSEL1;
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107 /* Setup baud rate low byte. */
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108 UCA1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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110 /* Setup baud rate high byte. */
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111 ulBaudRateCount >>= 8UL;
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112 UCA1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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114 /* UCLISTEN sets loopback mode! */
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115 UCA1STAT = UCLISTEN;
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117 /* Enable interrupts. */
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120 /* Take out of reset. */
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121 UCA1CTL1 &= ~UCSWRST;
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123 portEXIT_CRITICAL();
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125 /* Note the comments at the top of this file about this not being a generic
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129 /*-----------------------------------------------------------*/
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131 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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133 /* Get the next character from the buffer. Return false if no characters
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134 are available, or arrive before xBlockTime expires. */
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135 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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144 /*-----------------------------------------------------------*/
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146 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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148 signed portBASE_TYPE xReturn;
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150 /* Send the next character to the queue of characters waiting transmission,
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151 then enable the UART Tx interrupt, just in case UART transmission has already
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152 completed and switched itself off. */
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153 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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158 /*-----------------------------------------------------------*/
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160 /* The implementation of this interrupt is provided to demonstrate the use
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161 of queues from inside an interrupt service routine. It is *not* intended to
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162 be an efficient interrupt implementation. A real application should make use
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163 of the DMA. Or, as a minimum, transmission and reception could use a simple
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164 RAM ring buffer, and synchronise with a task using a semaphore when a complete
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165 message has been received or transmitted. */
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166 #pragma vector=USCI_A1_VECTOR
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167 static __interrupt void prvUSCI_A1_ISR( void )
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170 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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172 while( ( UCA1IFG & UCRXIFG ) != 0 )
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174 /* Get the character from the UART and post it on the queue of Rxed
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177 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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180 /* If there is a Tx interrupt pending and the tx interrupts are enabled. */
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181 if( ( UCA1IFG & UCTXIFG ) != 0 )
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183 /* The previous character has been transmitted. See if there are any
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184 further characters waiting transmission. */
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185 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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187 /* There was another character queued - transmit it now. */
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192 /* There were no other characters to transmit - disable the Tx
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198 __bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF );
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200 /* If writing to a queue caused a task to unblock, and the unblocked task
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201 has a priority equal to or above the task that this interrupt interrupted,
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202 then lHigherPriorityTaskWoken will have been set to pdTRUE internally within
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203 xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this
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204 interrupt returns directly to the higher priority unblocked task.
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206 THIS MUST BE THE LAST THING DONE IN THE ISR. */
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207 portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
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