2 FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
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4 ***************************************************************************
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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23 ***************************************************************************
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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 exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 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 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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56 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART0.
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58 This file contains all the serial port components that must be compiled
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59 to ARM mode. The components that can be compiled to either ARM or THUMB
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60 mode are contained in serial.c.
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64 /* Standard includes. */
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67 /* Scheduler includes. */
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68 #include "FreeRTOS.h"
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72 /* Demo application includes. */
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74 #include "AT91R40008.h"
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77 /*-----------------------------------------------------------*/
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79 /* Constant to access the AIC. */
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80 #define serCLEAR_AIC_INTERRUPT ( ( unsigned long ) 0 )
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82 /* Constants to determine the ISR source. */
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83 #define serSOURCE_THRE ( ( unsigned char ) 0x02 )
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84 #define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
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85 #define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
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86 #define serSOURCE_RX ( ( unsigned char ) 0x04 )
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87 #define serINTERRUPT_SOURCE_MASK ( ( unsigned long ) (US_RXRDY | US_TXRDY | US_RXBRK | US_OVRE | US_FRAME | US_PARE) )
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89 /* Queues used to hold received characters, and characters waiting to be
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91 static xQueueHandle xRxedChars;
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92 static xQueueHandle xCharsForTx;
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94 /*-----------------------------------------------------------*/
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96 /* UART0 interrupt service routine. This can cause a context switch so MUST
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97 be declared "naked". */
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98 void vUART_ISR_Wrapper( void ) __attribute__ ((naked));
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100 /* The ISR function that actually performs the work. This must be separate
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101 from the wrapper to ensure the correct stack frame is set up. */
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102 void vUART_ISR_Handler( void ) __attribute__ ((noinline));
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104 /*-----------------------------------------------------------*/
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105 void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx )
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107 /* Create the queues used to hold Rx and Tx characters. */
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108 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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109 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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111 /* Pass back a reference to the queues so the serial API file can
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112 post/receive characters. */
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113 *pxRxedChars = xRxedChars;
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114 *pxCharsForTx = xCharsForTx;
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116 /*-----------------------------------------------------------*/
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118 void vUART_ISR_Wrapper( void )
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120 /* Save the context of the interrupted task. */
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121 portSAVE_CONTEXT();
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123 /* Call the handler. This must be a separate function to ensure the
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124 stack frame is correctly set up. */
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125 __asm volatile( "bl vUART_ISR_Handler" );
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127 /* Restore the context of whichever task will run next. */
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128 portRESTORE_CONTEXT();
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130 /*-----------------------------------------------------------*/
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132 void vUART_ISR_Handler( void )
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134 /* Now we can declare the local variables. These must be static. */
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136 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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137 unsigned long ulStatus;
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139 /* What caused the interrupt? */
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140 ulStatus = AT91C_BASE_US0->US_CSR & AT91C_BASE_US0->US_IMR;
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142 if (ulStatus & US_TXRDY)
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144 /* The interrupt was caused by the THR becoming empty. Are there any
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145 more characters to transmit? */
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146 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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148 /* A character was retrieved from the queue so can be sent to the
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150 AT91C_BASE_US0->US_THR = cChar;
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154 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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155 AT91C_BASE_US0->US_IDR = US_TXRDY;
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159 if (ulStatus & US_RXRDY)
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161 /* The interrupt was caused by the receiver getting data. */
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162 cChar = AT91C_BASE_US0->US_RHR;
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164 xQueueSendFromISR(xRxedChars, &cChar, &xHigherPriorityTaskWoken);
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167 /* Acknowledge the interrupt at AIC level... */
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168 AT91C_BASE_AIC->AIC_EOICR = serCLEAR_AIC_INTERRUPT;
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170 /* If an event caused a task to unblock then we call "Yield from ISR" to
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171 ensure that the unblocked task is the task that executes when the interrupt
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172 completes if the unblocked task has a priority higher than the interrupted
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174 if( xHigherPriorityTaskWoken )
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176 portYIELD_FROM_ISR();
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179 /*-----------------------------------------------------------*/
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