2 FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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6 ***************************************************************************
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8 * FreeRTOS provides completely free yet professionally developed, *
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9 * robust, strictly quality controlled, supported, and cross *
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10 * platform software that has become a de facto standard. *
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12 * Help yourself get started quickly and support the FreeRTOS *
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13 * project by purchasing a FreeRTOS tutorial book, reference *
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14 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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18 ***************************************************************************
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20 This file is part of the FreeRTOS distribution.
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22 FreeRTOS is free software; you can redistribute it and/or modify it under
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23 the terms of the GNU General Public License (version 2) as published by the
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24 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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26 >>! NOTE: The modification to the GPL is included to allow you to distribute
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27 >>! a combined work that includes FreeRTOS without being obliged to provide
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28 >>! the source code for proprietary components outside of the FreeRTOS
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31 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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32 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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33 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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34 link: http://www.freertos.org/a00114.html
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38 ***************************************************************************
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40 * Having a problem? Start by reading the FAQ "My application does *
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41 * not run, what could be wrong?" *
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43 * http://www.FreeRTOS.org/FAQHelp.html *
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45 ***************************************************************************
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47 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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48 license and Real Time Engineers Ltd. contact details.
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50 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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51 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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52 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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54 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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55 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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56 licenses offer ticketed support, indemnification and middleware.
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58 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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59 engineered and independently SIL3 certified version for use in safety and
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60 mission critical applications that require provable dependability.
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66 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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69 /* Standard includes. */
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72 /* Scheduler includes. */
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73 #include "FreeRTOS.h"
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76 /* Demo application includes. */
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79 /*-----------------------------------------------------------*/
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81 /* Location of the COM0 registers. */
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82 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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84 /* Interrupt control macros. */
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85 #define serINTERRUPT_LEVEL ( 5 )
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86 #define vInterruptOn() AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )
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87 #define vInterruptOff() AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )
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89 /* Misc constants. */
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90 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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91 #define serHANDLE ( ( xComPortHandle ) 1 )
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92 #define serNO_BLOCK ( ( portTickType ) 0 )
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93 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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94 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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97 /* Queues used to hold received characters, and characters waiting to be
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99 static xQueueHandle xRxedChars;
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100 static xQueueHandle xCharsForTx;
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102 /*-----------------------------------------------------------*/
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104 /* Interrupt entry point written in the assembler file serialISR.s79. */
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105 extern void vSerialISREntry( void );
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107 /* The interrupt service routine - called from the assembly entry point. */
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108 __arm void vSerialISR( void );
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110 /*-----------------------------------------------------------*/
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113 * See the serial2.h header file.
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115 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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117 xComPortHandle xReturn = serHANDLE;
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118 extern void ( vUART_ISR )( void );
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120 /* Create the queues used to hold Rx and Tx characters. */
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121 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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122 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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124 /* If the queues were created correctly then setup the serial port
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126 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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128 portENTER_CRITICAL();
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130 /* Enable the USART clock. */
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131 AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );
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133 AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned long ) AT91C_PA5_RXD0 ) | ( ( unsigned long ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );
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135 /* Set the required protocol. */
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136 AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );
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138 /* Enable Rx and Tx. */
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139 serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
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141 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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142 until there are characters to be transmitted. */
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143 AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );
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145 /* Enable the interrupts in the AIC. */
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146 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );
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147 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );
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149 portEXIT_CRITICAL();
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153 xReturn = ( xComPortHandle ) 0;
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156 /* This demo file only supports a single port but we have to return
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157 something to comply with the standard demo header file. */
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160 /*-----------------------------------------------------------*/
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162 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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164 /* The port handle is not required as this driver only supports one port. */
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167 /* Get the next character from the buffer. Return false if no characters
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168 are available, or arrive before xBlockTime expires. */
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169 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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178 /*-----------------------------------------------------------*/
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180 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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182 signed char *pxNext;
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184 /* A couple of parameters that this port does not use. */
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185 ( void ) usStringLength;
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188 /* NOTE: This implementation does not handle the queue being full as no
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189 block time is used! */
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191 /* The port handle is not required as this driver only supports UART0. */
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194 /* Send each character in the string, one at a time. */
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195 pxNext = ( signed char * ) pcString;
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198 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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202 /*-----------------------------------------------------------*/
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204 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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206 /* Place the character in the queue of characters to be transmitted. */
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207 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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212 /* Turn on the Tx interrupt so the ISR will remove the character from the
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213 queue and send it. This does not need to be in a critical section as
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214 if the interrupt has already removed the character the next interrupt
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215 will simply turn off the Tx interrupt again. */
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220 /*-----------------------------------------------------------*/
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222 void vSerialClose( xComPortHandle xPort )
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224 /* Not supported as not required by the demo application. */
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226 /*-----------------------------------------------------------*/
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228 /* Serial port ISR. This can cause a context switch so is not defined as a
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229 standard ISR using the __irq keyword. Instead a wrapper function is defined
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230 within serialISR.s79 which in turn calls this function. See the port
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231 documentation on the FreeRTOS.org website for more information. */
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232 __arm void vSerialISR( void )
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234 unsigned long ulStatus;
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236 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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238 /* What caused the interrupt? */
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239 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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241 if( ulStatus & AT91C_US_TXRDY )
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243 /* The interrupt was caused by the THR becoming empty. Are there any
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244 more characters to transmit? */
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245 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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247 /* A character was retrieved from the queue so can be sent to the
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249 serCOM0->US_THR = cChar;
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253 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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258 if( ulStatus & AT91C_US_RXRDY )
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260 /* The interrupt was caused by a character being received. Grab the
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261 character from the RHR and place it in the queue or received
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263 cChar = serCOM0->US_RHR;
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264 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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267 /* If a task was woken by either a character being received or a character
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268 being transmitted then we may need to switch to another task. */
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269 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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271 /* End the interrupt in the AIC. */
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272 AT91C_BASE_AIC->AIC_EOICR = 0;
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