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.
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78 * This is not a proper UART driver. It only supports one port, uses loopback
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79 * mode, and is used to test interrupts that use the FreeRTOS API as part of
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80 * a wider test suite. Nor is it intended to show an efficient implementation
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81 * of a UART interrupt service routine as queues are used to pass individual
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82 * characters one at a time!
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85 /* Standard includes. */
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88 /* Scheduler includes. */
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89 #include "FreeRTOS.h"
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93 /* Demo application includes. */
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96 /* Misc. constants. */
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97 #define serNO_BLOCK ( ( portTickType ) 0 )
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99 /* The queue used to hold received characters. */
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100 static xQueueHandle xRxedChars;
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102 /* The queue used to hold characters waiting transmission. */
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103 static xQueueHandle xCharsForTx;
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105 /*-----------------------------------------------------------*/
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107 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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109 unsigned portLONG ulBaudRateCount;
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111 /* Initialise the hardware. */
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113 /* Generate the baud rate constants for the wanted baud rate. */
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114 ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud;
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116 portENTER_CRITICAL();
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118 /* Create the queues used by the com test task. */
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119 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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120 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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123 UCA1CTL1 |= UCSWRST;
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126 UCA1CTL1 = UCSSEL0 | UCSSEL1;
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128 /* Setup baud rate low byte. */
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129 UCA1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned long ) 0xff );
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131 /* Setup baud rate high byte. */
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132 ulBaudRateCount >>= 8UL;
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133 UCA1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned long ) 0xff );
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135 /* UCLISTEN sets loopback mode! */
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136 UCA1STAT = UCLISTEN;
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138 /* Enable interrupts. */
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141 /* Take out of reset. */
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142 UCA1CTL1 &= ~UCSWRST;
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144 portEXIT_CRITICAL();
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146 /* Note the comments at the top of this file about this not being a generic
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150 /*-----------------------------------------------------------*/
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152 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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154 /* Get the next character from the buffer. Return false if no characters
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155 are available, or arrive before xBlockTime expires. */
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156 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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165 /*-----------------------------------------------------------*/
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167 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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169 signed portBASE_TYPE xReturn;
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171 /* Send the next character to the queue of characters waiting transmission,
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172 then enable the UART Tx interrupt, just in case UART transmission has already
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173 completed and switched itself off. */
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174 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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179 /*-----------------------------------------------------------*/
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181 /* The implementation of this interrupt is provided to demonstrate the use
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182 of queues from inside an interrupt service routine. It is *not* intended to
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183 be an efficient interrupt implementation. A real application should make use
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184 of the DMA. Or, as a minimum, transmission and reception could use a simple
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185 RAM ring buffer, and synchronise with a task using a semaphore when a complete
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186 message has been received or transmitted. */
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187 #pragma vector=USCI_A1_VECTOR
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188 interrupt void prvUSCI_A1_ISR( void )
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191 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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193 if( ( UCA1IFG & UCRXIFG ) != 0 )
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195 /* Get the character from the UART and post it on the queue of Rxed
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198 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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200 else if( ( UCA1IFG & UCTXIFG ) != 0 )
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202 /* The previous character has been transmitted. See if there are any
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203 further characters waiting transmission. */
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204 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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206 /* There was another character queued - transmit it now. */
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211 /* There were no other characters to transmit - disable the Tx
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217 __bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF );
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219 /* If writing to a queue caused a task to unblock, and the unblocked task
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220 has a priority equal to or above the task that this interrupt interrupted,
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221 then lHigherPriorityTaskWoken will have been set to pdTRUE internally within
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222 xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this
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223 interrupt returns directly to the higher priority unblocked task.
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225 THIS MUST BE THE LAST THING DONE IN THE ISR. */
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226 portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
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