2 FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * The FreeRTOS eBook and reference manual are available to purchase for a *
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29 * small fee. Help yourself get started quickly while also helping the *
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30 * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
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32 ***************************************************************************
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36 Please ensure to read the configuration and relevant port sections of the
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37 online documentation.
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39 http://www.FreeRTOS.org - Documentation, latest information, license and
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42 http://www.SafeRTOS.com - A version that is certified for use in safety
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45 http://www.OpenRTOS.com - Commercial support, development, porting,
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46 licensing and training services.
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51 * BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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53 * This file only supports UART 2
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56 /* Standard includes. */
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59 /* Scheduler includes. */
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60 #include "FreeRTOS.h"
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64 /* Demo application includes. */
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67 /* The queue used to hold received characters. */
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68 static xQueueHandle xRxedChars;
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70 /* The queue used to hold characters waiting transmission. */
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71 static xQueueHandle xCharsForTx;
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73 static volatile portSHORT sTHREEmpty;
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75 /*-----------------------------------------------------------*/
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77 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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79 portENTER_CRITICAL();
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81 /* Create the queues used by the com test task. */
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82 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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83 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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85 /* Initialize UART asynchronous mode */
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86 BGR02 = configPER_CLOCK_HZ / ulWantedBaud;
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88 SCR02 = 0x17; /* 8N1 */
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89 SMR02 = 0x0d; /* enable SOT3, Reset, normal mode */
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90 SSR02 = 0x02; /* LSB first, enable receive interrupts */
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92 PFR20_D0 = 1; /* enable UART */
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93 PFR20_D1 = 1; /* enable UART */
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95 EPFR20_D1 = 0; /* enable UART */
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97 portEXIT_CRITICAL();
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99 /* Unlike other ports, this serial code does not allow for more than one
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100 com port. We therefore don't return a pointer to a port structure and can
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101 instead just return NULL. */
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104 /*-----------------------------------------------------------*/
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106 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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108 /* Get the next character from the buffer. Return false if no characters
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109 are available, or arrive before xBlockTime expires. */
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110 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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119 /*-----------------------------------------------------------*/
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121 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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123 signed portBASE_TYPE xReturn;
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125 /* Transmit a character. */
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126 portENTER_CRITICAL();
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128 if( sTHREEmpty == pdTRUE )
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130 /* If sTHREEmpty is true then the UART Tx ISR has indicated that
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131 there are no characters queued to be transmitted - so we can
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132 write the character directly to the shift Tx register. */
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133 sTHREEmpty = pdFALSE;
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139 /* sTHREEmpty is false, so there are still characters waiting to be
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140 transmitted. We have to queue this character so it gets
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141 transmitted in turn. */
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143 /* Return false if after the block time there is no room on the Tx
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144 queue. It is ok to block inside a critical section as each task
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145 maintains it's own critical section status. */
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146 if (xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdTRUE)
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156 if (pdPASS == xReturn)
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158 /* Turn on the Tx interrupt so the ISR will remove the character from the
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159 queue and send it. This does not need to be in a critical section as
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160 if the interrupt has already removed the character the next interrupt
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161 will simply turn off the Tx interrupt again. */
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166 portEXIT_CRITICAL();
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170 /*-----------------------------------------------------------*/
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173 * UART RX interrupt service routine.
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175 __interrupt void UART2_RxISR (void)
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177 signed portCHAR cChar;
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178 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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180 /* Get the character from the UART and post it on the queue of Rxed
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184 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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186 if( xHigherPriorityTaskWoken )
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188 /*If the post causes a task to wake force a context switch
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189 as the woken task may have a higher priority than the task we have
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191 portYIELD_FROM_ISR();
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195 /*-----------------------------------------------------------*/
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198 * UART Tx interrupt service routine.
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200 __interrupt void UART2_TxISR (void)
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202 signed portCHAR cChar;
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203 signed portBASE_TYPE xTaskWoken = pdFALSE;
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205 /* The previous character has been transmitted. See if there are any
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206 further characters waiting transmission. */
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207 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE )
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209 /* There was another character queued - transmit it now. */
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214 /* There were no other characters to transmit. */
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215 sTHREEmpty = pdTRUE;
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217 /* Disable transmit interrupts */
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