2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 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 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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31 * This is a concise, step by step, 'hands on' guide that describes both *
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32 * general multitasking concepts and FreeRTOS specifics. It presents and *
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33 * explains numerous examples that are written using the FreeRTOS API. *
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34 * Full source code for all the examples is provided in an accompanying *
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37 ***************************************************************************
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38 ***************************************************************************
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40 Please ensure to read the configuration and relevant port sections of the
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41 online documentation.
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43 http://www.FreeRTOS.org - Documentation, latest information, license and
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46 http://www.SafeRTOS.com - A version that is certified for use in safety
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49 http://www.OpenRTOS.com - Commercial support, development, porting,
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50 licensing and training services.
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54 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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56 * This file only supports UART 1
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59 /* Standard includes. */
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63 /* Scheduler includes. */
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64 #include "FreeRTOS.h"
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68 /* Demo application includes. */
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71 /* Constants required to setup the hardware. */
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72 #define serTX_AND_RX ( ( unsigned portCHAR ) 0x03 )
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74 /* Misc. constants. */
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75 #define serNO_BLOCK ( ( portTickType ) 0 )
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77 /* Enable the UART Tx interrupt. */
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78 #define vInterruptOn() IFG2 |= UTXIFG1
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80 /* The queue used to hold received characters. */
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81 static xQueueHandle xRxedChars;
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83 /* The queue used to hold characters waiting transmission. */
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84 static xQueueHandle xCharsForTx;
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86 static volatile portSHORT sTHREEmpty;
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88 /* Interrupt service routines. */
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89 interrupt (UART1RX_VECTOR) wakeup vRxISR( void );
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90 interrupt (UART1TX_VECTOR) wakeup vTxISR( void );
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92 /*-----------------------------------------------------------*/
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94 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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96 unsigned portLONG ulBaudRateCount;
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98 /* Initialise the hardware. */
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100 /* Generate the baud rate constants for the wanted baud rate. */
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101 ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
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103 portENTER_CRITICAL();
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105 /* Create the queues used by the com test task. */
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106 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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107 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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112 /* Set pin function. */
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113 P4SEL |= serTX_AND_RX;
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115 /* All other bits remain at zero for n, 8, 1 interrupt driven operation.
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117 U1CTL |= CHAR + LISTEN;
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120 /* Setup baud rate low byte. */
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121 U1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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123 /* Setup baud rate high byte. */
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124 ulBaudRateCount >>= 8UL;
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125 U1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff );
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127 /* Enable ports. */
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128 ME2 |= UTXE1 + URXE1;
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133 /* Nothing in the buffer yet. */
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134 sTHREEmpty = pdTRUE;
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136 /* Enable interrupts. */
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137 IE2 |= URXIE1 + UTXIE1;
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139 portEXIT_CRITICAL();
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141 /* Unlike other ports, this serial code does not allow for more than one
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142 com port. We therefore don't return a pointer to a port structure and can
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143 instead just return NULL. */
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146 /*-----------------------------------------------------------*/
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148 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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150 /* Get the next character from the buffer. Return false if no characters
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151 are available, or arrive before xBlockTime expires. */
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152 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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161 /*-----------------------------------------------------------*/
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163 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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165 signed portBASE_TYPE xReturn;
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167 /* Transmit a character. */
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169 portENTER_CRITICAL();
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171 if( sTHREEmpty == pdTRUE )
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173 /* If sTHREEmpty is true then the UART Tx ISR has indicated that
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174 there are no characters queued to be transmitted - so we can
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175 write the character directly to the shift Tx register. */
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176 sTHREEmpty = pdFALSE;
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177 U1TXBUF = cOutChar;
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182 /* sTHREEmpty is false, so there are still characters waiting to be
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183 transmitted. We have to queue this character so it gets
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184 transmitted in turn. */
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186 /* Return false if after the block time there is no room on the Tx
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187 queue. It is ok to block inside a critical section as each task
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188 maintains it's own critical section status. */
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189 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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191 /* Depending on queue sizing and task prioritisation: While we
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192 were blocked waiting to post on the queue interrupts were not
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193 disabled. It is possible that the serial ISR has emptied the
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194 Tx queue, in which case we need to start the Tx off again
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195 writing directly to the Tx register. */
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196 if( ( sTHREEmpty == pdTRUE ) && ( xReturn == pdPASS ) )
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198 /* Get back the character we just posted. */
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199 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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200 sTHREEmpty = pdFALSE;
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201 U1TXBUF = cOutChar;
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205 portEXIT_CRITICAL();
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209 /*-----------------------------------------------------------*/
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212 * UART RX interrupt service routine.
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214 interrupt (UART1RX_VECTOR) wakeup vRxISR( void )
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216 signed portCHAR cChar;
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217 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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219 /* Get the character from the UART and post it on the queue of Rxed
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223 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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225 if( xHigherPriorityTaskWoken )
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227 /*If the post causes a task to wake force a context switch
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228 as the woken task may have a higher priority than the task we have
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233 /*-----------------------------------------------------------*/
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236 * UART Tx interrupt service routine.
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238 interrupt (UART1TX_VECTOR) wakeup vTxISR( void )
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240 signed portCHAR cChar;
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241 portBASE_TYPE xTaskWoken = pdFALSE;
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243 /* The previous character has been transmitted. See if there are any
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244 further characters waiting transmission. */
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246 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE )
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248 /* There was another character queued - transmit it now. */
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253 /* There were no other characters to transmit. */
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254 sTHREEmpty = pdTRUE;
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