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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70 + Made serial ISR handling more complete and robust.
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74 + Split serial.c into serial.c and serialISR.c. serial.c can be
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75 compiled using ARM or THUMB modes. serialISR.c must always be
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76 compiled in ARM mode.
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77 + Another small change to cSerialPutChar().
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81 + In cSerialPutChar() an extra check is made to ensure the post to
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82 the queue was successful if then attempting to retrieve the posted
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88 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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90 This file contains all the serial port components that can be compiled to
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91 either ARM or THUMB mode. Components that must be compiled to ARM mode are
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92 contained in serialISR.c.
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95 /* Standard includes. */
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98 /* Scheduler includes. */
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99 #include "FreeRTOS.h"
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103 /* Demo application includes. */
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104 #include "serial.h"
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106 /*-----------------------------------------------------------*/
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108 /* Constants to setup and access the UART. */
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109 #define serDLAB ( ( unsigned char ) 0x80 )
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110 #define serENABLE_INTERRUPTS ( ( unsigned char ) 0x03 )
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111 #define serNO_PARITY ( ( unsigned char ) 0x00 )
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112 #define ser1_STOP_BIT ( ( unsigned char ) 0x00 )
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113 #define ser8_BIT_CHARS ( ( unsigned char ) 0x03 )
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114 #define serFIFO_ON ( ( unsigned char ) 0x01 )
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115 #define serCLEAR_FIFO ( ( unsigned char ) 0x06 )
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116 #define serWANTED_CLOCK_SCALING ( ( unsigned long ) 16 )
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118 /* Constants to setup and access the VIC. */
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119 #define serUART0_VIC_CHANNEL ( ( unsigned long ) 0x0006 )
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120 #define serUART0_VIC_CHANNEL_BIT ( ( unsigned long ) 0x0040 )
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121 #define serUART0_VIC_ENABLE ( ( unsigned long ) 0x0020 )
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122 #define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 )
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124 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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125 #define serHANDLE ( ( xComPortHandle ) 1 )
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126 #define serNO_BLOCK ( ( portTickType ) 0 )
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128 /*-----------------------------------------------------------*/
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130 /* Queues used to hold received characters, and characters waiting to be
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132 static xQueueHandle xRxedChars;
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133 static xQueueHandle xCharsForTx;
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135 /*-----------------------------------------------------------*/
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137 /* Communication flag between the interrupt service routine and serial API. */
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138 static volatile long *plTHREEmpty;
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141 * The queues are created in serialISR.c as they are used from the ISR.
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142 * Obtain references to the queues and THRE Empty flag.
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144 extern void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, long volatile **pplTHREEmptyFlag );
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146 /*-----------------------------------------------------------*/
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148 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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150 unsigned long ulDivisor, ulWantedClock;
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151 xComPortHandle xReturn = serHANDLE;
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152 extern void ( vUART_ISR_Wrapper )( void );
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154 /* The queues are used in the serial ISR routine, so are created from
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155 serialISR.c (which is always compiled to ARM mode. */
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156 vSerialISRCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx, &plTHREEmpty );
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159 ( xRxedChars != serINVALID_QUEUE ) &&
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160 ( xCharsForTx != serINVALID_QUEUE ) &&
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161 ( ulWantedBaud != ( unsigned long ) 0 )
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164 portENTER_CRITICAL();
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166 /* Setup the baud rate: Calculate the divisor value. */
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167 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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168 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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170 /* Set the DLAB bit so we can access the divisor. */
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171 UART0_LCR |= serDLAB;
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173 /* Setup the divisor. */
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174 UART0_DLL = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );
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176 UART0_DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );
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178 /* Turn on the FIFO's and clear the buffers. */
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179 UART0_FCR = ( serFIFO_ON | serCLEAR_FIFO );
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181 /* Setup transmission format. */
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182 UART0_LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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184 /* Setup the VIC for the UART. */
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185 VICIntSelect &= ~( serUART0_VIC_CHANNEL_BIT );
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186 VICIntEnable |= serUART0_VIC_CHANNEL_BIT;
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187 VICVectAddr1 = ( long ) vUART_ISR_Wrapper;
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188 VICVectCntl1 = serUART0_VIC_CHANNEL | serUART0_VIC_ENABLE;
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190 /* Enable UART0 interrupts. */
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191 UART0_IER |= serENABLE_INTERRUPTS;
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193 portEXIT_CRITICAL();
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197 xReturn = ( xComPortHandle ) 0;
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202 /*-----------------------------------------------------------*/
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204 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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206 /* The port handle is not required as this driver only supports UART0. */
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209 /* Get the next character from the buffer. Return false if no characters
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210 are available, or arrive before xBlockTime expires. */
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211 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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220 /*-----------------------------------------------------------*/
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222 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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224 signed char *pxNext;
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226 /* NOTE: This implementation does not handle the queue being full as no
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227 block time is used! */
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229 /* The port handle is not required as this driver only supports UART0. */
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231 ( void ) usStringLength;
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233 /* Send each character in the string, one at a time. */
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234 pxNext = ( signed char * ) pcString;
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237 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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241 /*-----------------------------------------------------------*/
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243 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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245 signed portBASE_TYPE xReturn;
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247 /* This demo driver only supports one port so the parameter is not used. */
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250 portENTER_CRITICAL();
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252 /* Is there space to write directly to the UART? */
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253 if( *plTHREEmpty == ( long ) pdTRUE )
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255 /* We wrote the character directly to the UART, so was
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257 *plTHREEmpty = pdFALSE;
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258 UART0_THR = cOutChar;
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263 /* We cannot write directly to the UART, so queue the character.
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264 Block for a maximum of xBlockTime if there is no space in the
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266 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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268 /* Depending on queue sizing and task prioritisation: While we
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269 were blocked waiting to post interrupts were not disabled. It is
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270 possible that the serial ISR has emptied the Tx queue, in which
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271 case we need to start the Tx off again. */
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272 if( ( *plTHREEmpty == ( long ) pdTRUE ) && ( xReturn == pdPASS ) )
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274 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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275 *plTHREEmpty = pdFALSE;
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276 UART0_THR = cOutChar;
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280 portEXIT_CRITICAL();
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284 /*-----------------------------------------------------------*/
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286 void vSerialClose( xComPortHandle xPort )
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288 /* Not supported as not required by the demo application. */
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291 /*-----------------------------------------------------------*/
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