2 FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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77 * Creates a task and a timer that operate on an interrupt driven serial port.
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78 * This demo assumes that the characters transmitted on a port will also be
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79 * received on the same port. Therefore, the UART must either be connected to
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80 * an echo server, or the uart connector must have a loopback connector fitted.
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81 * See http://www.serialporttool.com/CommEcho.htm for a suitable echo server
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82 * for Windows hosts.
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84 * The timer sends a string to the UART, toggles an LED, then resets itself by
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85 * changing its own period. The period is calculated as a pseudo random number
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86 * between comTX_MAX_BLOCK_TIME and comTX_MIN_BLOCK_TIME.
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88 * The task blocks on an Rx queue waiting for a character to become available.
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89 * Received characters are checked to ensure they match those transmitted by the
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90 * Tx timer. An error is latched if characters are missing, incorrect, or
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91 * arrive too slowly.
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93 * How characters are actually transmitted and received is port specific. Demos
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94 * that include this test/demo file will provide example drivers. The Tx timer
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95 * executes in the context of the timer service (daemon) task, and must
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96 * therefore never attempt to block.
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100 /* Scheduler include files. */
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101 #include <stdlib.h>
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102 #include <string.h>
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103 #include "FreeRTOS.h"
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105 #include "timers.h"
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107 #ifndef configUSE_TIMERS
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108 #error This demo uses timers. configUSE_TIMERS must be set to 1 in FreeRTOSConfig.h.
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111 #if configUSE_TIMERS != 1
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112 #error This demo uses timers. configUSE_TIMERS must be set to 1 in FreeRTOSConfig.h.
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116 /* Demo program include files. */
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117 #include "serial.h"
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118 #include "comtest_strings.h"
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119 #include "partest.h"
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121 /* The size of the stack given to the Rx task. */
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122 #define comSTACK_SIZE configMINIMAL_STACK_SIZE
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124 /* See the comment above the declaraction of the uxBaseLED variable. */
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125 #define comTX_LED_OFFSET ( 0 )
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126 #define comRX_LED_OFFSET ( 1 )
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128 /* The Tx timer transmits the sequence of characters at a pseudo random
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129 interval that is capped between comTX_MAX_BLOCK_TIME and
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130 comTX_MIN_BLOCK_TIME. */
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131 #define comTX_MAX_BLOCK_TIME ( ( portTickType ) 0x96 )
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132 #define comTX_MIN_BLOCK_TIME ( ( portTickType ) 0x32 )
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133 #define comOFFSET_TIME ( ( portTickType ) 3 )
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135 /* States for the simple state machine implemented in the Rx task. */
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136 #define comtstWAITING_START_OF_STRING 0
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137 #define comtstWAITING_END_OF_STRING 1
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139 /* A short delay in ticks - this delay is used to allow the Rx queue to fill up
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140 a bit so more than one character can be processed at a time. This is relative
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141 to comTX_MIN_BLOCK_TIME to ensure it is never longer than the shortest gap
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142 between transmissions. It could be worked out more scientifically from the
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143 baud rate being used. */
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144 #define comSHORT_DELAY ( comTX_MIN_BLOCK_TIME >> ( portTickType ) 2 )
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146 /* The string that is transmitted and received. */
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147 #define comTRANSACTED_STRING "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
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149 /* A block time of 0 simply means "don't block". */
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150 #define comtstDONT_BLOCK ( portTickType ) 0
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152 /* Handle to the com port used by both tasks. */
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153 static xComPortHandle xPort = NULL;
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155 /* The callback function allocated to the transmit timer, as described in the
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156 comments at the top of this file. */
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157 static void prvComTxTimerCallback( xTimerHandle xTimer );
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159 /* The receive task as described in the comments at the top of this file. */
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160 static void vComRxTask( void *pvParameters );
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162 /* The Rx task will toggle LED ( uxBaseLED + comRX_LED_OFFSET). The Tx task
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163 will toggle LED ( uxBaseLED + comTX_LED_OFFSET ). */
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164 static unsigned portBASE_TYPE uxBaseLED = 0;
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166 /* The Rx task toggles uxRxLoops on each successful iteration of its defined
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167 function - provided no errors have ever been latched. If this variable stops
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168 incrementing, then an error has occurred. */
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169 static volatile unsigned portBASE_TYPE uxRxLoops = 0UL;
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171 /* The timer used to periodically transmit the string. This is the timer that
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172 has prvComTxTimerCallback allocated to it as its callback function. */
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173 static xTimerHandle xTxTimer = NULL;
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175 /* The string length is held at file scope so the Tx timer does not need to
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176 calculate it each time it executes. */
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177 static size_t xStringLength = 0U;
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179 /*-----------------------------------------------------------*/
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181 void vStartComTestStringsTasks( unsigned portBASE_TYPE uxPriority, unsigned long ulBaudRate, unsigned portBASE_TYPE uxLED )
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183 /* Store values that are used at run time. */
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186 /* Calculate the string length here, rather than each time the Tx timer
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188 xStringLength = strlen( comTRANSACTED_STRING );
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190 /* Include the null terminator in the string length as this is used to
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191 detect the end of the string in the Rx task. */
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194 /* Initialise the com port, then spawn the Rx task and create the Tx
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196 xSerialPortInitMinimal( ulBaudRate, ( xStringLength * 2U ) );
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198 /* Create the Rx task and the Tx timer. The timer is started from the
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200 xTaskCreate( vComRxTask, ( signed char * ) "COMRx", comSTACK_SIZE, NULL, uxPriority, ( xTaskHandle * ) NULL );
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201 xTxTimer = xTimerCreate( ( const signed char * ) "TxTimer", comTX_MIN_BLOCK_TIME, pdFALSE, NULL, prvComTxTimerCallback );
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202 configASSERT( xTxTimer );
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204 /*-----------------------------------------------------------*/
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206 static void prvComTxTimerCallback( xTimerHandle xTimer )
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208 portTickType xTimeToWait;
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210 /* The parameter is not used in this case. */
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213 /* Send the string. How this is actually performed depends on the
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214 sample driver provided with this demo. However - as this is a timer,
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215 it executes in the context of the timer task and therefore must not
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217 vSerialPutString( xPort, ( const signed char * const ) comTRANSACTED_STRING, xStringLength );
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219 /* Toggle an LED to give a visible indication that another transmission
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220 has been performed. */
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221 vParTestToggleLED( uxBaseLED + comTX_LED_OFFSET );
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223 /* Wait a pseudo random time before sending the string again. */
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224 xTimeToWait = xTaskGetTickCount() + comOFFSET_TIME;
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226 /* Ensure the time to wait is not greater than comTX_MAX_BLOCK_TIME. */
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227 xTimeToWait %= comTX_MAX_BLOCK_TIME;
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229 /* Ensure the time to wait is not less than comTX_MIN_BLOCK_TIME. */
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230 if( xTimeToWait < comTX_MIN_BLOCK_TIME )
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232 xTimeToWait = comTX_MIN_BLOCK_TIME;
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235 /* Reset the timer to run again xTimeToWait ticks from now. This function
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236 is called from the context of the timer task, so the block time must not
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237 be anything other than zero. */
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238 xTimerChangePeriod( xTxTimer, xTimeToWait, comtstDONT_BLOCK );
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240 /*-----------------------------------------------------------*/
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242 static void vComRxTask( void *pvParameters )
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244 portBASE_TYPE xState = comtstWAITING_START_OF_STRING, xErrorOccurred = pdFALSE;
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245 signed char *pcExpectedByte, cRxedChar;
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246 const xComPortHandle xPort = NULL;
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248 /* The parameter is not used in this example. */
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249 ( void ) pvParameters;
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251 /* Start the Tx timer. This only needs to be started once, as it will
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252 reset itself thereafter. */
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253 xTimerStart( xTxTimer, portMAX_DELAY );
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255 /* The first expected Rx character is the first in the string that is
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257 pcExpectedByte = ( signed char * ) comTRANSACTED_STRING;
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261 /* Wait for the next character. */
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262 if( xSerialGetChar( xPort, &cRxedChar, ( comTX_MAX_BLOCK_TIME * 2 ) ) == pdFALSE )
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264 /* A character definitely should have been received by now. As a
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265 character was not received an error must have occurred (which might
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266 just be that the loopback connector is not fitted). */
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267 xErrorOccurred = pdTRUE;
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272 case comtstWAITING_START_OF_STRING:
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273 if( cRxedChar == *pcExpectedByte )
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275 /* The received character was the first character of the
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276 string. Move to the next state to check each character
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277 as it comes in until the entire string has been received. */
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278 xState = comtstWAITING_END_OF_STRING;
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281 /* Block for a short period. This just allows the Rx queue
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282 to contain more than one character, and therefore prevent
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283 thrashing reads to the queue, and repetitive context
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284 switches as each character is received. */
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285 vTaskDelay( comSHORT_DELAY );
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289 case comtstWAITING_END_OF_STRING:
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290 if( cRxedChar == *pcExpectedByte )
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292 /* The received character was the expected character. Was
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293 it the last character in the string - i.e. the null
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295 if( cRxedChar == 0x00 )
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297 /* The entire string has been received. If no errors
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298 have been latched, then increment the loop counter to
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299 show this task is still healthy. */
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300 if( xErrorOccurred == pdFALSE )
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304 /* Toggle an LED to give a visible sign that a
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305 complete string has been received. */
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306 vParTestToggleLED( uxBaseLED + comRX_LED_OFFSET );
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309 /* Go back to wait for the start of the next string. */
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310 pcExpectedByte = ( signed char * ) comTRANSACTED_STRING;
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311 xState = comtstWAITING_START_OF_STRING;
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315 /* Wait for the next character in the string. */
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321 /* The character received was not that expected. */
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322 xErrorOccurred = pdTRUE;
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327 /* Should not get here. Stop the Rx loop counter from
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328 incrementing to latch the error. */
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329 xErrorOccurred = pdTRUE;
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334 /*-----------------------------------------------------------*/
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336 portBASE_TYPE xAreComTestTasksStillRunning( void )
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338 portBASE_TYPE xReturn;
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340 /* If the count of successful reception loops has not changed than at
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341 some time an error occurred (i.e. a character was received out of sequence)
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342 and false is returned. */
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343 if( uxRxLoops == 0UL )
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352 /* Reset the count of successful Rx loops. When this function is called
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353 again it should have been incremented again. */
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projects / freertos / blob