2 FreeRTOS V7.2.0 - Copyright (C) 2012 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 ***************************************************************************
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46 * Having a problem? Start by reading the FAQ "My application does *
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47 * not run, what could be wrong? *
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49 * http://www.FreeRTOS.org/FAQHelp.html *
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51 ***************************************************************************
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54 http://www.FreeRTOS.org - Documentation, training, latest information,
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55 license and contact details.
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57 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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58 including FreeRTOS+Trace - an indispensable productivity tool.
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60 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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61 the code with commercial support, indemnification, and middleware, under
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62 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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63 provide a safety engineered and independently SIL3 certified version under
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64 the SafeRTOS brand: http://www.SafeRTOS.com.
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69 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART0.
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71 This file contains all the serial port components that must be compiled
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72 to ARM mode. The components that can be compiled to either ARM or THUMB
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73 mode are contained in serial.c.
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77 /* Standard includes. */
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80 /* Scheduler includes. */
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81 #include "FreeRTOS.h"
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85 /* Demo application includes. */
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87 #include "AT91R40008.h"
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90 /*-----------------------------------------------------------*/
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92 /* Constant to access the AIC. */
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93 #define serCLEAR_AIC_INTERRUPT ( ( unsigned long ) 0 )
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95 /* Constants to determine the ISR source. */
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96 #define serSOURCE_THRE ( ( unsigned char ) 0x02 )
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97 #define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
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98 #define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
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99 #define serSOURCE_RX ( ( unsigned char ) 0x04 )
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100 #define serINTERRUPT_SOURCE_MASK ( ( unsigned long ) (US_RXRDY | US_TXRDY | US_RXBRK | US_OVRE | US_FRAME | US_PARE) )
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102 /* Queues used to hold received characters, and characters waiting to be
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104 static xQueueHandle xRxedChars;
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105 static xQueueHandle xCharsForTx;
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107 /*-----------------------------------------------------------*/
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109 /* UART0 interrupt service routine. This can cause a context switch so MUST
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110 be declared "naked". */
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111 void vUART_ISR_Wrapper( void ) __attribute__ ((naked));
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113 /* The ISR function that actually performs the work. This must be separate
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114 from the wrapper to ensure the correct stack frame is set up. */
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115 void vUART_ISR_Handler( void ) __attribute__ ((noinline));
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117 /*-----------------------------------------------------------*/
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118 void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx )
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120 /* Create the queues used to hold Rx and Tx characters. */
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121 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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122 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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124 /* Pass back a reference to the queues so the serial API file can
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125 post/receive characters. */
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126 *pxRxedChars = xRxedChars;
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127 *pxCharsForTx = xCharsForTx;
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129 /*-----------------------------------------------------------*/
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131 void vUART_ISR_Wrapper( void )
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133 /* Save the context of the interrupted task. */
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134 portSAVE_CONTEXT();
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136 /* Call the handler. This must be a separate function to ensure the
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137 stack frame is correctly set up. */
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138 __asm volatile( "bl vUART_ISR_Handler" );
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140 /* Restore the context of whichever task will run next. */
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141 portRESTORE_CONTEXT();
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143 /*-----------------------------------------------------------*/
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145 void vUART_ISR_Handler( void )
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147 /* Now we can declare the local variables. These must be static. */
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149 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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150 unsigned long ulStatus;
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152 /* What caused the interrupt? */
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153 ulStatus = AT91C_BASE_US0->US_CSR & AT91C_BASE_US0->US_IMR;
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155 if (ulStatus & US_TXRDY)
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157 /* The interrupt was caused by the THR becoming empty. Are there any
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158 more characters to transmit? */
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159 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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161 /* A character was retrieved from the queue so can be sent to the
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163 AT91C_BASE_US0->US_THR = cChar;
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167 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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168 AT91C_BASE_US0->US_IDR = US_TXRDY;
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172 if (ulStatus & US_RXRDY)
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174 /* The interrupt was caused by the receiver getting data. */
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175 cChar = AT91C_BASE_US0->US_RHR;
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177 xQueueSendFromISR(xRxedChars, &cChar, &xHigherPriorityTaskWoken);
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180 /* Acknowledge the interrupt at AIC level... */
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181 AT91C_BASE_AIC->AIC_EOICR = serCLEAR_AIC_INTERRUPT;
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183 /* If an event caused a task to unblock then we call "Yield from ISR" to
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184 ensure that the unblocked task is the task that executes when the interrupt
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185 completes if the unblocked task has a priority higher than the interrupted
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187 if( xHigherPriorityTaskWoken )
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189 portYIELD_FROM_ISR();
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192 /*-----------------------------------------------------------*/
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