2 FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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67 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART0.
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69 This file contains all the serial port components that must be compiled
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70 to ARM mode. The components that can be compiled to either ARM or THUMB
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71 mode are contained in serial.c.
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75 /* Standard includes. */
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78 /* Scheduler includes. */
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79 #include "FreeRTOS.h"
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83 /* Demo application includes. */
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85 #include "AT91R40008.h"
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88 /*-----------------------------------------------------------*/
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90 /* Constant to access the AIC. */
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91 #define serCLEAR_AIC_INTERRUPT ( ( unsigned long ) 0 )
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93 /* Constants to determine the ISR source. */
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94 #define serSOURCE_THRE ( ( unsigned char ) 0x02 )
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95 #define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
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96 #define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
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97 #define serSOURCE_RX ( ( unsigned char ) 0x04 )
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98 #define serINTERRUPT_SOURCE_MASK ( ( unsigned long ) (US_RXRDY | US_TXRDY | US_RXBRK | US_OVRE | US_FRAME | US_PARE) )
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100 /* Queues used to hold received characters, and characters waiting to be
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102 static xQueueHandle xRxedChars;
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103 static xQueueHandle xCharsForTx;
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105 /*-----------------------------------------------------------*/
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107 /* UART0 interrupt service routine. This can cause a context switch so MUST
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108 be declared "naked". */
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109 void vUART_ISR_Wrapper( void ) __attribute__ ((naked));
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111 /* The ISR function that actually performs the work. This must be separate
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112 from the wrapper to ensure the correct stack frame is set up. */
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113 void vUART_ISR_Handler( void ) __attribute__ ((noinline));
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115 /*-----------------------------------------------------------*/
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116 void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx )
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118 /* Create the queues used to hold Rx and Tx characters. */
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119 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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120 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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122 /* Pass back a reference to the queues so the serial API file can
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123 post/receive characters. */
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124 *pxRxedChars = xRxedChars;
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125 *pxCharsForTx = xCharsForTx;
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127 /*-----------------------------------------------------------*/
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129 void vUART_ISR_Wrapper( void )
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131 /* Save the context of the interrupted task. */
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132 portSAVE_CONTEXT();
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134 /* Call the handler. This must be a separate function to ensure the
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135 stack frame is correctly set up. */
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136 __asm volatile( "bl vUART_ISR_Handler" );
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138 /* Restore the context of whichever task will run next. */
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139 portRESTORE_CONTEXT();
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141 /*-----------------------------------------------------------*/
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143 void vUART_ISR_Handler( void )
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145 /* Now we can declare the local variables. These must be static. */
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147 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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148 unsigned long ulStatus;
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150 /* What caused the interrupt? */
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151 ulStatus = AT91C_BASE_US0->US_CSR & AT91C_BASE_US0->US_IMR;
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153 if (ulStatus & US_TXRDY)
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155 /* The interrupt was caused by the THR becoming empty. Are there any
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156 more characters to transmit? */
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157 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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159 /* A character was retrieved from the queue so can be sent to the
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161 AT91C_BASE_US0->US_THR = cChar;
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165 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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166 AT91C_BASE_US0->US_IDR = US_TXRDY;
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170 if (ulStatus & US_RXRDY)
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172 /* The interrupt was caused by the receiver getting data. */
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173 cChar = AT91C_BASE_US0->US_RHR;
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175 xQueueSendFromISR(xRxedChars, &cChar, &xHigherPriorityTaskWoken);
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178 /* Acknowledge the interrupt at AIC level... */
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179 AT91C_BASE_AIC->AIC_EOICR = serCLEAR_AIC_INTERRUPT;
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181 /* If an event caused a task to unblock then we call "Yield from ISR" to
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182 ensure that the unblocked task is the task that executes when the interrupt
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183 completes if the unblocked task has a priority higher than the interrupted
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185 if( xHigherPriorityTaskWoken )
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187 portYIELD_FROM_ISR();
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190 /*-----------------------------------------------------------*/
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