2 FreeRTOS V7.0.0 - Copyright (C) 2011 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 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 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 0
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59 /* Standard includes. */
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62 /* Scheduler includes. */
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63 #include "FreeRTOS.h"
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67 /* Demo application includes. */
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70 /* The queue used to hold received characters. */
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71 static xQueueHandle xRxedChars;
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73 /* The queue used to hold characters waiting transmission. */
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74 static xQueueHandle xCharsForTx;
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76 static volatile portSHORT sTHREEmpty;
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78 static volatile portSHORT queueFail = pdFALSE;
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80 /*-----------------------------------------------------------*/
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81 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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83 /* Initialise the hardware. */
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84 portENTER_CRITICAL();
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86 /* Create the queues used by the com test task. */
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87 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof(signed portCHAR) );
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88 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof(signed portCHAR) );
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90 if( xRxedChars == 0 )
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95 if( xCharsForTx == 0 )
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100 /* Initialize UART asynchronous mode */
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101 BGR0 = configCLKP1_CLOCK_HZ / ulWantedBaud;
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103 SCR0 = 0x17; /* 8N1 */
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104 SMR0 = 0x0d; /* enable SOT3, Reset, normal mode */
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105 SSR0 = 0x02; /* LSB first, enable receive interrupts */
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107 PIER08_IE2 = 1; /* enable input */
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108 DDR08_D2 = 0; /* switch P08_2 to input */
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109 DDR08_D3 = 1; /* switch P08_3 to output */
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111 portEXIT_CRITICAL();
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113 /* Unlike other ports, this serial code does not allow for more than one
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114 com port. We therefore don't return a pointer to a port structure and can
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115 instead just return NULL. */
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118 /*-----------------------------------------------------------*/
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120 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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122 /* Get the next character from the buffer. Return false if no characters
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123 are available, or arrive before xBlockTime expires. */
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124 if( xQueueReceive(xRxedChars, pcRxedChar, xBlockTime) )
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133 /*-----------------------------------------------------------*/
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135 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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137 signed portBASE_TYPE xReturn;
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139 /* Transmit a character. */
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140 portENTER_CRITICAL();
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142 if( sTHREEmpty == pdTRUE )
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144 /* If sTHREEmpty is true then the UART Tx ISR has indicated that
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145 there are no characters queued to be transmitted - so we can
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146 write the character directly to the shift Tx register. */
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147 sTHREEmpty = pdFALSE;
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153 /* sTHREEmpty is false, so there are still characters waiting to be
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154 transmitted. We have to queue this character so it gets
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155 transmitted in turn. */
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157 /* Return false if after the block time there is no room on the Tx
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158 queue. It is ok to block inside a critical section as each task
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159 maintains it's own critical section status. */
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160 if( xQueueSend(xCharsForTx, &cOutChar, xBlockTime) == pdTRUE )
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170 if( pdPASS == xReturn )
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172 /* Turn on the Tx interrupt so the ISR will remove the character from the
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173 queue and send it. This does not need to be in a critical section as
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174 if the interrupt has already removed the character the next interrupt
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175 will simply turn off the Tx interrupt again. */
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179 portEXIT_CRITICAL();
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183 /*-----------------------------------------------------------*/
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186 * UART RX interrupt service routine.
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188 __interrupt void UART0_RxISR( void )
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190 volatile signed portCHAR cChar;
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191 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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193 /* Get the character from the UART and post it on the queue of Rxed
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197 xQueueSendFromISR( xRxedChars, ( const void *const ) &cChar, &xHigherPriorityTaskWoken );
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199 if( xHigherPriorityTaskWoken )
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201 /*If the post causes a task to wake force a context switch
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202 as the woken task may have a higher priority than the task we have
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204 portYIELD_FROM_ISR();
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207 /*-----------------------------------------------------------*/
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210 * UART Tx interrupt service routine.
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212 __interrupt void UART0_TxISR( void )
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214 signed portCHAR cChar;
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215 signed portBASE_TYPE xTaskWoken = pdFALSE;
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217 /* The previous character has been transmitted. See if there are any
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218 further characters waiting transmission. */
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219 if( xQueueReceiveFromISR(xCharsForTx, &cChar, &xTaskWoken) == pdTRUE )
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221 /* There was another character queued - transmit it now. */
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226 /* There were no other characters to transmit. */
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227 sTHREEmpty = pdTRUE;
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229 /* Disable transmit interrupts */
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