2 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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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 exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 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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55 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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57 * This file only supports UART 1
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60 /* Standard includes. */
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64 /* Scheduler includes. */
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65 #include "FreeRTOS.h"
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69 /* Demo application includes. */
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72 /* Constants required to setup the hardware. */
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73 #define serTX_AND_RX ( ( unsigned char ) 0x03 )
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75 /* Misc. constants. */
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76 #define serNO_BLOCK ( ( portTickType ) 0 )
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78 /* Enable the UART Tx interrupt. */
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79 #define vInterruptOn() IFG2 |= UTXIFG1
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81 /* The queue used to hold received characters. */
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82 static xQueueHandle xRxedChars;
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84 /* The queue used to hold characters waiting transmission. */
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85 static xQueueHandle xCharsForTx;
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87 static volatile short sTHREEmpty;
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89 /* Interrupt service routines. */
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90 interrupt (UART1RX_VECTOR) wakeup vRxISR( void );
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91 interrupt (UART1TX_VECTOR) wakeup vTxISR( void );
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93 /*-----------------------------------------------------------*/
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95 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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97 unsigned long ulBaudRateCount;
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99 /* Initialise the hardware. */
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101 /* Generate the baud rate constants for the wanted baud rate. */
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102 ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
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104 portENTER_CRITICAL();
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106 /* Create the queues used by the com test task. */
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107 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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108 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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113 /* Set pin function. */
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114 P4SEL |= serTX_AND_RX;
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116 /* All other bits remain at zero for n, 8, 1 interrupt driven operation.
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118 U1CTL |= CHAR + LISTEN;
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121 /* Setup baud rate low byte. */
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122 U1BR0 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff );
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124 /* Setup baud rate high byte. */
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125 ulBaudRateCount >>= 8UL;
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126 U1BR1 = ( unsigned char ) ( ulBaudRateCount & ( unsigned long ) 0xff );
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128 /* Enable ports. */
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129 ME2 |= UTXE1 + URXE1;
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134 /* Nothing in the buffer yet. */
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135 sTHREEmpty = pdTRUE;
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137 /* Enable interrupts. */
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138 IE2 |= URXIE1 + UTXIE1;
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140 portEXIT_CRITICAL();
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142 /* Unlike other ports, this serial code does not allow for more than one
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143 com port. We therefore don't return a pointer to a port structure and can
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144 instead just return NULL. */
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147 /*-----------------------------------------------------------*/
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149 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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151 /* Get the next character from the buffer. Return false if no characters
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152 are available, or arrive before xBlockTime expires. */
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153 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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162 /*-----------------------------------------------------------*/
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164 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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166 signed portBASE_TYPE xReturn;
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168 /* Transmit a character. */
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170 portENTER_CRITICAL();
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172 if( sTHREEmpty == pdTRUE )
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174 /* If sTHREEmpty is true then the UART Tx ISR has indicated that
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175 there are no characters queued to be transmitted - so we can
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176 write the character directly to the shift Tx register. */
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177 sTHREEmpty = pdFALSE;
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178 U1TXBUF = cOutChar;
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183 /* sTHREEmpty is false, so there are still characters waiting to be
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184 transmitted. We have to queue this character so it gets
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185 transmitted in turn. */
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187 /* Return false if after the block time there is no room on the Tx
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188 queue. It is ok to block inside a critical section as each task
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189 maintains it's own critical section status. */
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190 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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192 /* Depending on queue sizing and task prioritisation: While we
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193 were blocked waiting to post on the queue interrupts were not
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194 disabled. It is possible that the serial ISR has emptied the
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195 Tx queue, in which case we need to start the Tx off again
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196 writing directly to the Tx register. */
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197 if( ( sTHREEmpty == pdTRUE ) && ( xReturn == pdPASS ) )
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199 /* Get back the character we just posted. */
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200 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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201 sTHREEmpty = pdFALSE;
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202 U1TXBUF = cOutChar;
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206 portEXIT_CRITICAL();
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210 /*-----------------------------------------------------------*/
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213 * UART RX interrupt service routine.
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215 interrupt (UART1RX_VECTOR) wakeup vRxISR( void )
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218 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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220 /* Get the character from the UART and post it on the queue of Rxed
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224 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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226 if( xHigherPriorityTaskWoken )
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228 /*If the post causes a task to wake force a context switch
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229 as the woken task may have a higher priority than the task we have
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234 /*-----------------------------------------------------------*/
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237 * UART Tx interrupt service routine.
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239 interrupt (UART1TX_VECTOR) wakeup vTxISR( void )
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242 portBASE_TYPE xTaskWoken = pdFALSE;
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244 /* The previous character has been transmitted. See if there are any
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245 further characters waiting transmission. */
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247 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE )
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249 /* There was another character queued - transmit it now. */
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254 /* There were no other characters to transmit. */
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255 sTHREEmpty = pdTRUE;
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