2 FreeRTOS V7.4.0 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not itcan be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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79 /* Standard includes. */
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82 /* Scheduler includes. */
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83 #include "FreeRTOS.h"
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86 /* Demo application includes. */
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89 /* Atmel library includes. */
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90 #include <usart/usart.h>
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91 #include <aic/aic.h>
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92 #include <pmc/pmc.h>
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94 /*-----------------------------------------------------------*/
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96 /* Location of the COM0 registers. */
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97 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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99 /* Interrupt control macros. */
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100 #define serINTERRUPT_LEVEL ( 5 )
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101 #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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102 #define vInterruptOff() serCOM0->US_IDR = AT91C_US_TXRDY
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104 /* Misc constants. */
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105 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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106 #define serHANDLE ( ( xComPortHandle ) 1 )
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107 #define serNO_BLOCK ( ( portTickType ) 0 )
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108 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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109 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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112 /* Queues used to hold received characters, and characters waiting to be
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114 static xQueueHandle xRxedChars;
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115 static xQueueHandle xCharsForTx;
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117 /*-----------------------------------------------------------*/
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119 /* The interrupt service routine. */
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120 __arm void vSerialISR( void );
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122 /*-----------------------------------------------------------*/
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125 * See the serial2.h header file.
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127 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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129 xComPortHandle xReturn = serHANDLE;
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131 /* Create the queues used to hold Rx and Tx characters. */
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132 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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133 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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135 /* If the queues were created correctly then setup the serial port
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137 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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139 PMC_EnablePeripheral( AT91C_ID_US0 );
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140 portENTER_CRITICAL();
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142 USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
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144 /* Enable Rx and Tx. */
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145 USART_SetTransmitterEnabled( serCOM0, pdTRUE );
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146 USART_SetReceiverEnabled( serCOM0, pdTRUE );
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148 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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149 until there are characters to be transmitted. */
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150 serCOM0->US_IER = AT91C_US_RXRDY;
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152 /* Enable the interrupts in the AIC. */
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153 AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
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154 AIC_EnableIT( AT91C_ID_US0 );
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156 portEXIT_CRITICAL();
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160 xReturn = ( xComPortHandle ) 0;
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163 /* This demo file only supports a single port but we have to return
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164 something to comply with the standard demo header file. */
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167 /*-----------------------------------------------------------*/
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169 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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171 /* The port handle is not required as this driver only supports one port. */
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174 /* Get the next character from the buffer. Return false if no characters
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175 are available, or arrive before xBlockTime expires. */
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176 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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185 /*-----------------------------------------------------------*/
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187 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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189 signed char *pxNext;
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191 /* A couple of parameters that this port does not use. */
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192 ( void ) usStringLength;
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195 /* NOTE: This implementation does not handle the queue being full as no
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196 block time is used! */
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198 /* The port handle is not required as this driver only supports UART0. */
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201 /* Send each character in the string, one at a time. */
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202 pxNext = ( signed char * ) pcString;
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205 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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209 /*-----------------------------------------------------------*/
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211 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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213 /* Just to remove compiler warning. */
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216 /* Place the character in the queue of characters to be transmitted. */
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217 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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222 /* Turn on the Tx interrupt so the ISR will remove the character from the
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223 queue and send it. This does not need to be in a critical section as
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224 if the interrupt has already removed the character the next interrupt
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225 will simply turn off the Tx interrupt again. */
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230 /*-----------------------------------------------------------*/
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232 void vSerialClose( xComPortHandle xPort )
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234 /* Not supported as not required by the demo application. */
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237 /*-----------------------------------------------------------*/
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239 /* Serial port ISR. This can cause a context switch so is not defined as a
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240 standard ISR using the __irq keyword. Instead a wrapper function is defined
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241 within serialISR.s79 which in turn calls this function. See the port
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242 documentation on the FreeRTOS.org website for more information. */
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243 __arm void vSerialISR( void )
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245 unsigned long ulStatus;
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247 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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249 /* What caused the interrupt? */
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250 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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252 if( ulStatus & AT91C_US_TXRDY )
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254 /* The interrupt was caused by the THR becoming empty. Are there any
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255 more characters to transmit? */
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256 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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258 /* A character was retrieved from the queue so can be sent to the
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260 serCOM0->US_THR = cChar;
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264 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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269 if( ulStatus & AT91C_US_RXRDY )
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271 /* The interrupt was caused by a character being received. Grab the
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272 character from the RHR and place it in the queue or received
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274 cChar = serCOM0->US_RHR;
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275 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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278 /* If a task was woken by either a character being received or a character
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279 being transmitted then we may need to switch to another task. */
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280 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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282 /* End the interrupt in the AIC. */
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283 AT91C_BASE_AIC->AIC_EOICR = 0;
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