2 FreeRTOS V7.1.1 - 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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68 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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70 ***Note*** This example uses queues to send each character into an interrupt
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71 service routine and out of an interrupt service routine individually. This
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72 is done to demonstrate queues being used in an interrupt, and to deliberately
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73 load the system to test the FreeRTOS port. It is *NOT* meant to be an
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74 example of an efficient implementation. An efficient implementation should
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75 use FIFO's or DMA if available, and only use FreeRTOS API functions when
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76 enough has been received to warrant a task being unblocked to process the
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80 /* Scheduler includes. */
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81 #include "FreeRTOS.h"
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84 #include "comtest2.h"
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86 /* Library includes. */
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87 #include "stm32l152_eval.h"
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89 /* Demo application includes. */
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91 /*-----------------------------------------------------------*/
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94 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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95 #define serNO_BLOCK ( ( portTickType ) 0 )
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97 /*-----------------------------------------------------------*/
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99 /* The queue used to hold received characters. */
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100 static xQueueHandle xRxedChars;
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101 static xQueueHandle xCharsForTx;
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103 /*-----------------------------------------------------------*/
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106 * See the serial2.h header file.
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108 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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110 USART_InitTypeDef USART_InitStructure;
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111 xComPortHandle xReturn;
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112 NVIC_InitTypeDef NVIC_InitStructure;
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114 /* Create the queues used to hold Rx/Tx characters. */
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115 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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116 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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118 /* If the queues were created correctly then setup the serial port
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120 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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122 USART_InitStructure.USART_BaudRate = ulWantedBaud;
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123 USART_InitStructure.USART_WordLength = USART_WordLength_8b;
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124 USART_InitStructure.USART_StopBits = USART_StopBits_1;
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125 USART_InitStructure.USART_Parity = USART_Parity_No;
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126 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
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127 USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
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129 /* The Eval board COM2 is being used, which in reality is the STM32
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131 STM_EVAL_COMInit( COM2, &USART_InitStructure );
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133 NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
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134 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY;
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135 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; /* Not used as 4 bits are used for the pre-emption priority. */;
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136 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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137 NVIC_Init( &NVIC_InitStructure );
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138 USART_ITConfig( USART3, USART_IT_RXNE, ENABLE );
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142 xReturn = ( xComPortHandle ) 0;
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145 /* This demo file only supports a single port but we have to return
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146 something to comply with the standard demo header file. */
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149 /*-----------------------------------------------------------*/
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151 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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153 /* The port handle is not required as this driver only supports one port. */
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156 /* Get the next character from the buffer. Return false if no characters
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157 are available, or arrive before xBlockTime expires. */
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158 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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167 /*-----------------------------------------------------------*/
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169 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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171 signed portCHAR *pxNext;
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173 /* A couple of parameters that this port does not use. */
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174 ( void ) usStringLength;
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177 /* NOTE: This implementation does not handle the queue being full as no
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178 block time is used! */
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180 /* The port handle is not required as this driver only supports UART1. */
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183 /* Send each character in the string, one at a time. */
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184 pxNext = ( signed portCHAR * ) pcString;
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187 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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191 /*-----------------------------------------------------------*/
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193 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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195 signed portBASE_TYPE xReturn;
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197 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS )
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200 USART_ITConfig( USART3, USART_IT_TXE, ENABLE );
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209 /*-----------------------------------------------------------*/
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211 void vSerialClose( xComPortHandle xPort )
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213 /* Not supported as not required by the demo application. */
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215 /*-----------------------------------------------------------*/
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217 void USART3_IRQHandler( void )
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219 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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222 if( USART_GetITStatus( USART3, USART_IT_TXE ) == SET )
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224 /* The interrupt was caused by the TX register becoming empty. Are
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225 there any more characters to transmit? */
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226 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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228 /* A character was retrieved from the queue so can be sent to the
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230 USART_SendData( USART3, cChar );
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234 USART_ITConfig( USART3, USART_IT_TXE, DISABLE );
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238 if( USART_GetITStatus( USART3, USART_IT_RXNE ) == SET )
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240 /* A character has been received on the USART, send it to the Rx
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242 cChar = USART_ReceiveData( USART3 );
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243 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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246 /* If sending or receiving from a queue has caused a task to unblock, and
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247 the unblocked task has a priority equal to or higher than the currently
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248 running task (the task this ISR interrupted), then xHigherPriorityTaskWoken
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249 will have automatically been set to pdTRUE within the queue send or receive
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250 function. portEND_SWITCHING_ISR() will then ensure that this ISR returns
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251 directly to the higher priority unblocked task. */
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252 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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