2 FreeRTOS.org V5.1.0 - Copyright (C) 2003-2008 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
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30 * and even write all or part of your application on your behalf. *
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31 * See http://www.OpenRTOS.com for details of the services we provide to *
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32 * expedite your project. *
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34 ***************************************************************************
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35 ***************************************************************************
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37 Please ensure to read the configuration and relevant port sections of the
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38 online documentation.
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40 http://www.FreeRTOS.org - Documentation, latest information, license and
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43 http://www.SafeRTOS.com - A version that is certified for use in safety
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46 http://www.OpenRTOS.com - Commercial support, development, porting,
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47 licensing and training services.
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52 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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54 Note this driver is used to test the FreeRTOS port. It is NOT intended to
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55 be an example of an efficient implementation!
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58 /* Standard includes. */
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61 /* Scheduler includes. */
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62 #include "FreeRTOS.h"
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66 /* Demo application includes. */
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69 /*-----------------------------------------------------------*/
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71 /* Constants to setup and access the UART. */
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72 #define serDLAB ( ( unsigned portCHAR ) 0x80 )
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73 #define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
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74 #define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
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75 #define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
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76 #define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
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77 #define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
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78 #define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
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79 #define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
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81 /* Constants to setup and access the VIC. */
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82 #define serU1VIC_CHANNEL ( ( unsigned portLONG ) 0x0007 )
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83 #define serU1VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0080 )
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84 #define serU1VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
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87 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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88 #define serHANDLE ( ( xComPortHandle ) 1 )
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89 #define serNO_BLOCK ( ( portTickType ) 0 )
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91 /* Constant to access the VIC. */
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92 #define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
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94 /* Constants to determine the ISR source. */
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95 #define serSOURCE_THRE ( ( unsigned portCHAR ) 0x02 )
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96 #define serSOURCE_RX_TIMEOUT ( ( unsigned portCHAR ) 0x0c )
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97 #define serSOURCE_ERROR ( ( unsigned portCHAR ) 0x06 )
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98 #define serSOURCE_RX ( ( unsigned portCHAR ) 0x04 )
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99 #define serINTERRUPT_SOURCE_MASK ( ( unsigned portCHAR ) 0x0f )
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100 #define serINTERRUPT_IS_PENDING ( ( unsigned portCHAR ) 0x01 )
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102 /*-----------------------------------------------------------*/
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105 * The asm wrapper for the interrupt service routine.
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107 extern void vUART_ISREntry( void );
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110 * The C function called from the asm wrapper.
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112 void vUART_ISRHandler( void );
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114 /*-----------------------------------------------------------*/
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116 /* Queues used to hold received characters, and characters waiting to be
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118 static xQueueHandle xRxedChars;
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119 static xQueueHandle xCharsForTx;
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121 /* Communication flag between the interrupt service routine and serial API. */
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122 static volatile portLONG lTHREEmpty;
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124 /*-----------------------------------------------------------*/
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126 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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128 unsigned portLONG ulDivisor, ulWantedClock;
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129 xComPortHandle xReturn = serHANDLE;
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131 /* Create the queues used to hold Rx and Tx characters. */
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132 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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133 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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135 /* Initialise the THRE empty flag. */
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136 lTHREEmpty = pdTRUE;
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139 ( xRxedChars != serINVALID_QUEUE ) &&
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140 ( xCharsForTx != serINVALID_QUEUE ) &&
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141 ( ulWantedBaud != ( unsigned portLONG ) 0 )
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144 portENTER_CRITICAL()
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146 /* Setup the baud rate: Calculate the divisor value. */
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147 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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148 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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150 /* Set the DLAB bit so we can access the divisor. */
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153 /* Setup the divisor. */
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154 U1DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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156 U1DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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158 /* Turn on the FIFO's and clear the buffers. */
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159 U1FCR = ( serFIFO_ON | serCLEAR_FIFO );
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161 /* Setup transmission format. */
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162 U1LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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164 /* Setup the VIC for the UART. */
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165 VICIntSelect &= ~( serU1VIC_CHANNEL_BIT );
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166 VICIntEnable |= serU1VIC_CHANNEL_BIT;
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167 VICVectAddr1 = ( unsigned portLONG ) vUART_ISREntry;
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168 VICVectCntl1 = serU1VIC_CHANNEL | serU1VIC_ENABLE;
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170 /* Enable UART0 interrupts. */
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171 U1IER |= serENABLE_INTERRUPTS;
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173 portEXIT_CRITICAL();
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177 xReturn = ( xComPortHandle ) 0;
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182 /*-----------------------------------------------------------*/
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184 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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186 /* The port handle is not required as this driver only supports UART0. */
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189 /* Get the next character from the buffer. Return false if no characters
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190 are available, or arrive before xBlockTime expires. */
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191 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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200 /*-----------------------------------------------------------*/
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202 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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204 signed portCHAR *pxNext;
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206 /* NOTE: This implementation does not handle the queue being full as no
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207 block time is used! */
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209 /* The port handle is not required as this driver only supports UART0. */
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211 ( void ) usStringLength;
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213 /* Send each character in the string, one at a time. */
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214 pxNext = ( signed portCHAR * ) pcString;
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217 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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221 /*-----------------------------------------------------------*/
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223 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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225 signed portBASE_TYPE xReturn;
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227 /* The port handle is not required as this driver only supports UART0. */
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230 portENTER_CRITICAL();
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232 /* Is there space to write directly to the UART? */
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233 if( lTHREEmpty == ( portLONG ) pdTRUE )
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235 /* We wrote the character directly to the UART, so was
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237 lTHREEmpty = pdFALSE;
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243 /* We cannot write directly to the UART, so queue the character.
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244 Block for a maximum of xBlockTime if there is no space in the
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245 queue. It is ok to block within a critical section as each
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246 task has it's own critical section management. */
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247 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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249 /* Depending on queue sizing and task prioritisation: While we
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250 were blocked waiting to post interrupts were not disabled. It is
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251 possible that the serial ISR has emptied the Tx queue, in which
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252 case we need to start the Tx off again. */
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253 if( lTHREEmpty == ( portLONG ) pdTRUE )
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255 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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256 lTHREEmpty = pdFALSE;
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261 portEXIT_CRITICAL();
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265 /*-----------------------------------------------------------*/
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267 void vUART_ISRHandler( void )
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269 signed portCHAR cChar;
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270 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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271 unsigned portCHAR ucInterrupt;
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273 ucInterrupt = U1IIR;
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275 /* The interrupt pending bit is active low. */
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276 while( ( ucInterrupt & serINTERRUPT_IS_PENDING ) == 0 )
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278 /* What caused the interrupt? */
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279 switch( ucInterrupt & serINTERRUPT_SOURCE_MASK )
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281 case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */
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285 case serSOURCE_THRE : /* The THRE is empty. If there is another
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286 character in the Tx queue, send it now. */
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287 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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293 /* There are no further characters
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294 queued to send so we can indicate
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295 that the THRE is available. */
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296 lTHREEmpty = pdTRUE;
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300 case serSOURCE_RX_TIMEOUT :
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301 case serSOURCE_RX : /* A character was received. Place it in
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302 the queue of received characters. */
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304 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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307 default : /* There is nothing to do, leave the ISR. */
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311 ucInterrupt = U1IIR;
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314 /* Clear the ISR in the VIC. */
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315 VICVectAddr = serCLEAR_VIC_INTERRUPT;
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317 /* Exit the ISR. If a task was woken by either a character being received
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318 or transmitted then a context switch will occur. */
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319 portEXIT_SWITCHING_ISR( xHigherPriorityTaskWoken );
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321 /*-----------------------------------------------------------*/
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