2 FreeRTOS.org V4.7.2 - Copyright (C) 2003-2008 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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28 Please ensure to read the configuration and relevant port sections of the
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29 online documentation.
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31 +++ http://www.FreeRTOS.org +++
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32 Documentation, latest information, license and contact details.
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34 +++ http://www.SafeRTOS.com +++
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35 A version that is certified for use in safety critical systems.
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37 +++ http://www.OpenRTOS.com +++
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38 Commercial support, development, porting, licensing and training services.
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40 ***************************************************************************
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46 + The function xPortInitMinimal() has been renamed to
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47 xSerialPortInitMinimal() and the function xPortInit() has been renamed
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48 to xSerialPortInit().
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52 + Delay periods are now specified using variables and constants of
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53 portTickType rather than unsigned portLONG.
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54 + xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.
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58 + Replaced the inb() and outb() functions with direct memory
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59 access. This allows the port to be built with the 20050414 build of
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63 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
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67 #include <avr/interrupt.h>
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68 #include "FreeRTOS.h"
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73 #define serBAUD_DIV_CONSTANT ( ( unsigned portLONG ) 16 )
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75 /* Constants for writing to UCSRB. */
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76 #define serRX_INT_ENABLE ( ( unsigned portCHAR ) 0x80 )
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77 #define serRX_ENABLE ( ( unsigned portCHAR ) 0x10 )
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78 #define serTX_ENABLE ( ( unsigned portCHAR ) 0x08 )
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79 #define serTX_INT_ENABLE ( ( unsigned portCHAR ) 0x20 )
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81 /* Constants for writing to UCSRC. */
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82 #define serUCSRC_SELECT ( ( unsigned portCHAR ) 0x80 )
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83 #define serEIGHT_DATA_BITS ( ( unsigned portCHAR ) 0x06 )
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85 static xQueueHandle xRxedChars;
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86 static xQueueHandle xCharsForTx;
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88 #define vInterruptOn() \
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90 unsigned portCHAR ucByte; \
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93 ucByte |= serTX_INT_ENABLE; \
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96 /*-----------------------------------------------------------*/
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98 #define vInterruptOff() \
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100 unsigned portCHAR ucInByte; \
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102 ucInByte = UCSRB; \
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103 ucInByte &= ~serTX_INT_ENABLE; \
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104 UCSRB = ucInByte; \
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106 /*-----------------------------------------------------------*/
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108 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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110 unsigned portLONG ulBaudRateCounter;
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111 unsigned portCHAR ucByte;
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113 portENTER_CRITICAL();
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115 /* Create the queues used by the com test task. */
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116 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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117 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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119 /* Calculate the baud rate register value from the equation in the
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121 ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned portLONG ) 1;
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123 /* Set the baud rate. */
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124 ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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127 ulBaudRateCounter >>= ( unsigned portLONG ) 8;
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128 ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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131 /* Enable the Rx interrupt. The Tx interrupt will get enabled
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132 later. Also enable the Rx and Tx. */
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133 UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );
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135 /* Set the data bits to 8. */
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136 UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );
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138 portEXIT_CRITICAL();
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140 /* Unlike other ports, this serial code does not allow for more than one
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141 com port. We therefore don't return a pointer to a port structure and can
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142 instead just return NULL. */
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145 /*-----------------------------------------------------------*/
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147 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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149 /* Only one port is supported. */
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152 /* Get the next character from the buffer. Return false if no characters
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153 are available, or arrive before xBlockTime expires. */
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154 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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163 /*-----------------------------------------------------------*/
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165 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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167 /* Only one port is supported. */
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170 /* Return false if after the block time there is no room on the Tx queue. */
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171 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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180 /*-----------------------------------------------------------*/
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182 void vSerialClose( xComPortHandle xPort )
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184 unsigned portCHAR ucByte;
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186 /* The parameter is not used. */
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189 /* Turn off the interrupts. We may also want to delete the queues and/or
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190 re-install the original ISR. */
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192 portENTER_CRITICAL();
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196 ucByte &= ~serRX_INT_ENABLE;
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199 portEXIT_CRITICAL();
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201 /*-----------------------------------------------------------*/
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203 SIGNAL( SIG_UART_RECV )
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205 signed portCHAR cChar;
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207 /* Get the character and post it on the queue of Rxed characters.
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208 If the post causes a task to wake force a context switch as the woken task
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209 may have a higher priority than the task we have interrupted. */
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212 if( xQueueSendFromISR( xRxedChars, &cChar, pdFALSE ) )
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217 /*-----------------------------------------------------------*/
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219 SIGNAL( SIG_UART_DATA )
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221 signed portCHAR cChar, cTaskWoken;
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223 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
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225 /* Send the next character queued for Tx. */
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230 /* Queue empty, nothing to send. */
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