2 FreeRTOS.org V5.3.1 - 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 it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the 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.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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55 + The function xPortInitMinimal() has been renamed to
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56 xSerialPortInitMinimal() and the function xPortInit() has been renamed
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57 to xSerialPortInit().
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61 + Delay periods are now specified using variables and constants of
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62 portTickType rather than unsigned portLONG.
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63 + xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.
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67 + Replaced the inb() and outb() functions with direct memory
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68 access. This allows the port to be built with the 20050414 build of
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72 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
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76 #include <avr/interrupt.h>
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77 #include "FreeRTOS.h"
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82 #define serBAUD_DIV_CONSTANT ( ( unsigned portLONG ) 16 )
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84 /* Constants for writing to UCSRB. */
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85 #define serRX_INT_ENABLE ( ( unsigned portCHAR ) 0x80 )
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86 #define serRX_ENABLE ( ( unsigned portCHAR ) 0x10 )
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87 #define serTX_ENABLE ( ( unsigned portCHAR ) 0x08 )
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88 #define serTX_INT_ENABLE ( ( unsigned portCHAR ) 0x20 )
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90 /* Constants for writing to UCSRC. */
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91 #define serUCSRC_SELECT ( ( unsigned portCHAR ) 0x80 )
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92 #define serEIGHT_DATA_BITS ( ( unsigned portCHAR ) 0x06 )
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94 static xQueueHandle xRxedChars;
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95 static xQueueHandle xCharsForTx;
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97 #define vInterruptOn() \
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99 unsigned portCHAR ucByte; \
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102 ucByte |= serTX_INT_ENABLE; \
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105 /*-----------------------------------------------------------*/
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107 #define vInterruptOff() \
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109 unsigned portCHAR ucInByte; \
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111 ucInByte = UCSRB; \
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112 ucInByte &= ~serTX_INT_ENABLE; \
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113 UCSRB = ucInByte; \
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115 /*-----------------------------------------------------------*/
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117 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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119 unsigned portLONG ulBaudRateCounter;
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120 unsigned portCHAR ucByte;
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122 portENTER_CRITICAL();
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124 /* Create the queues used by the com test task. */
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125 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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126 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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128 /* Calculate the baud rate register value from the equation in the
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130 ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned portLONG ) 1;
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132 /* Set the baud rate. */
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133 ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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136 ulBaudRateCounter >>= ( unsigned portLONG ) 8;
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137 ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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140 /* Enable the Rx interrupt. The Tx interrupt will get enabled
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141 later. Also enable the Rx and Tx. */
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142 UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );
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144 /* Set the data bits to 8. */
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145 UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );
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147 portEXIT_CRITICAL();
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149 /* Unlike other ports, this serial code does not allow for more than one
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150 com port. We therefore don't return a pointer to a port structure and can
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151 instead just return NULL. */
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154 /*-----------------------------------------------------------*/
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156 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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158 /* Only one port is supported. */
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161 /* Get the next character from the buffer. Return false if no characters
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162 are available, or arrive before xBlockTime expires. */
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163 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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172 /*-----------------------------------------------------------*/
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174 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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176 /* Only one port is supported. */
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179 /* Return false if after the block time there is no room on the Tx queue. */
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180 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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189 /*-----------------------------------------------------------*/
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191 void vSerialClose( xComPortHandle xPort )
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193 unsigned portCHAR ucByte;
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195 /* The parameter is not used. */
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198 /* Turn off the interrupts. We may also want to delete the queues and/or
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199 re-install the original ISR. */
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201 portENTER_CRITICAL();
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205 ucByte &= ~serRX_INT_ENABLE;
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208 portEXIT_CRITICAL();
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210 /*-----------------------------------------------------------*/
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212 SIGNAL( SIG_UART_RECV )
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214 signed portCHAR cChar;
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215 signed portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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217 /* Get the character and post it on the queue of Rxed characters.
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218 If the post causes a task to wake force a context switch as the woken task
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219 may have a higher priority than the task we have interrupted. */
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222 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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224 if( xHigherPriorityTaskWoken != pdFALSE )
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229 /*-----------------------------------------------------------*/
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231 SIGNAL( SIG_UART_DATA )
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233 signed portCHAR cChar, cTaskWoken;
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235 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
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237 /* Send the next character queued for Tx. */
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242 /* Queue empty, nothing to send. */
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