2 FreeRTOS V7.1.1 - Copyright (C) 2012 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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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 modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or 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 ***************************************************************************
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46 * Having a problem? Start by reading the FAQ "My application does *
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47 * not run, what could be wrong? *
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49 * http://www.FreeRTOS.org/FAQHelp.html *
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51 ***************************************************************************
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54 http://www.FreeRTOS.org - Documentation, training, latest information,
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55 license and contact details.
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57 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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58 including FreeRTOS+Trace - an indispensable productivity tool.
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60 Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
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61 the code with commercial support, indemnification, and middleware, under
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62 the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
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63 provide a safety engineered and independently SIL3 certified version under
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64 the SafeRTOS brand: http://www.SafeRTOS.com.
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68 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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71 /* Standard includes. */
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74 /* Scheduler includes. */
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75 #include "FreeRTOS.h"
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78 /* Demo application includes. */
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81 /*-----------------------------------------------------------*/
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83 /* Location of the COM0 registers. */
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84 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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86 /* Interrupt control macros. */
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87 #define serINTERRUPT_LEVEL ( 5 )
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88 #define vInterruptOn() AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )
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89 #define vInterruptOff() AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )
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91 /* Misc constants. */
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92 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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93 #define serHANDLE ( ( xComPortHandle ) 1 )
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94 #define serNO_BLOCK ( ( portTickType ) 0 )
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95 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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96 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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99 /* Queues used to hold received characters, and characters waiting to be
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101 static xQueueHandle xRxedChars;
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102 static xQueueHandle xCharsForTx;
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104 /*-----------------------------------------------------------*/
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106 /* Interrupt entry point written in the assembler file serialISR.s79. */
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107 extern void vSerialISREntry( void );
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109 /* The interrupt service routine - called from the assembly entry point. */
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110 __arm void vSerialISR( void );
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112 /*-----------------------------------------------------------*/
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115 * See the serial2.h header file.
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117 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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119 xComPortHandle xReturn = serHANDLE;
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120 extern void ( vUART_ISR )( void );
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122 /* Create the queues used to hold Rx and Tx characters. */
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123 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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124 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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126 /* If the queues were created correctly then setup the serial port
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128 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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130 portENTER_CRITICAL();
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132 /* Enable the USART clock. */
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133 AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );
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135 AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned long ) AT91C_PA5_RXD0 ) | ( ( unsigned long ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );
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137 /* Set the required protocol. */
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138 AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );
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140 /* Enable Rx and Tx. */
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141 serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
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143 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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144 until there are characters to be transmitted. */
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145 AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );
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147 /* Enable the interrupts in the AIC. */
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148 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );
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149 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );
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151 portEXIT_CRITICAL();
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155 xReturn = ( xComPortHandle ) 0;
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158 /* This demo file only supports a single port but we have to return
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159 something to comply with the standard demo header file. */
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162 /*-----------------------------------------------------------*/
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164 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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166 /* The port handle is not required as this driver only supports one port. */
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169 /* Get the next character from the buffer. Return false if no characters
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170 are available, or arrive before xBlockTime expires. */
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171 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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180 /*-----------------------------------------------------------*/
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182 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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184 signed char *pxNext;
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186 /* A couple of parameters that this port does not use. */
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187 ( void ) usStringLength;
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190 /* NOTE: This implementation does not handle the queue being full as no
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191 block time is used! */
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193 /* The port handle is not required as this driver only supports UART0. */
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196 /* Send each character in the string, one at a time. */
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197 pxNext = ( signed char * ) pcString;
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200 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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204 /*-----------------------------------------------------------*/
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206 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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208 /* Place the character in the queue of characters to be transmitted. */
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209 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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214 /* Turn on the Tx interrupt so the ISR will remove the character from the
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215 queue and send it. This does not need to be in a critical section as
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216 if the interrupt has already removed the character the next interrupt
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217 will simply turn off the Tx interrupt again. */
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222 /*-----------------------------------------------------------*/
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224 void vSerialClose( xComPortHandle xPort )
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226 /* Not supported as not required by the demo application. */
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228 /*-----------------------------------------------------------*/
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230 /* Serial port ISR. This can cause a context switch so is not defined as a
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231 standard ISR using the __irq keyword. Instead a wrapper function is defined
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232 within serialISR.s79 which in turn calls this function. See the port
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233 documentation on the FreeRTOS.org website for more information. */
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234 __arm void vSerialISR( void )
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236 unsigned long ulStatus;
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238 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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240 /* What caused the interrupt? */
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241 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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243 if( ulStatus & AT91C_US_TXRDY )
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245 /* The interrupt was caused by the THR becoming empty. Are there any
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246 more characters to transmit? */
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247 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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249 /* A character was retrieved from the queue so can be sent to the
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251 serCOM0->US_THR = cChar;
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255 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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260 if( ulStatus & AT91C_US_RXRDY )
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262 /* The interrupt was caused by a character being received. Grab the
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263 character from the RHR and place it in the queue or received
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265 cChar = serCOM0->US_RHR;
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266 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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269 /* If a task was woken by either a character being received or a character
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270 being transmitted then we may need to switch to another task. */
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271 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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273 /* End the interrupt in the AIC. */
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274 AT91C_BASE_AIC->AIC_EOICR = 0;
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