2 FreeRTOS V5.4.2 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 This file is part of the FreeRTOS distribution.
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6 FreeRTOS is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License (version 2) as published by the
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8 Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS without being obliged to provide the
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11 source code for proprietary components outside of the FreeRTOS kernel.
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12 Alternative commercial license and support terms are also available upon
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13 request. See the licensing section of http://www.FreeRTOS.org for full
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16 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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18 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 You should have received a copy of the GNU General Public License along
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22 with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
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23 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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26 ***************************************************************************
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28 * Looking for a quick start? Then check out the FreeRTOS eBook! *
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29 * See http://www.FreeRTOS.org/Documentation for details *
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31 ***************************************************************************
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35 Please ensure to read the configuration and relevant port sections of the
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36 online documentation.
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38 http://www.FreeRTOS.org - Documentation, latest information, license and
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41 http://www.SafeRTOS.com - A version that is certified for use in safety
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44 http://www.OpenRTOS.com - Commercial support, development, porting,
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45 licensing and training services.
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48 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER.
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50 * This file only supports UART 0
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53 /* Standard includes. */
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56 /* Scheduler includes. */
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57 #include "FreeRTOS.h"
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61 /* Demo application includes. */
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64 /* The queue used to hold received characters. */
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65 static xQueueHandle xRxedChars;
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67 /* The queue used to hold characters waiting transmission. */
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68 static xQueueHandle xCharsForTx;
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70 static volatile portSHORT sTHREEmpty;
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72 static volatile portSHORT queueFail = pdFALSE;
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74 /*-----------------------------------------------------------*/
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75 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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77 /* Initialise the hardware. */
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78 portENTER_CRITICAL();
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80 /* Create the queues used by the com test task. */
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81 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof(signed portCHAR) );
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82 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof(signed portCHAR) );
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84 if( xRxedChars == 0 )
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89 if( xCharsForTx == 0 )
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94 /* Initialize UART asynchronous mode */
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95 BGR0 = configCLKP1_CLOCK_HZ / ulWantedBaud;
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97 SCR0 = 0x17; /* 8N1 */
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98 SMR0 = 0x0d; /* enable SOT3, Reset, normal mode */
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99 SSR0 = 0x02; /* LSB first, enable receive interrupts */
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101 PIER08_IE2 = 1; /* enable input */
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102 DDR08_D2 = 0; /* switch P08_2 to input */
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103 DDR08_D3 = 1; /* switch P08_3 to output */
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105 portEXIT_CRITICAL();
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107 /* Unlike other ports, this serial code does not allow for more than one
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108 com port. We therefore don't return a pointer to a port structure and can
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109 instead just return NULL. */
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112 /*-----------------------------------------------------------*/
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114 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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116 /* Get the next character from the buffer. Return false if no characters
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117 are available, or arrive before xBlockTime expires. */
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118 if( xQueueReceive(xRxedChars, pcRxedChar, xBlockTime) )
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127 /*-----------------------------------------------------------*/
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129 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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131 signed portBASE_TYPE xReturn;
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133 /* Transmit a character. */
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134 portENTER_CRITICAL();
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136 if( sTHREEmpty == pdTRUE )
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138 /* If sTHREEmpty is true then the UART Tx ISR has indicated that
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139 there are no characters queued to be transmitted - so we can
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140 write the character directly to the shift Tx register. */
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141 sTHREEmpty = pdFALSE;
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147 /* sTHREEmpty is false, so there are still characters waiting to be
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148 transmitted. We have to queue this character so it gets
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149 transmitted in turn. */
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151 /* Return false if after the block time there is no room on the Tx
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152 queue. It is ok to block inside a critical section as each task
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153 maintains it's own critical section status. */
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154 if( xQueueSend(xCharsForTx, &cOutChar, xBlockTime) == pdTRUE )
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164 if( pdPASS == xReturn )
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166 /* Turn on the Tx interrupt so the ISR will remove the character from the
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167 queue and send it. This does not need to be in a critical section as
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168 if the interrupt has already removed the character the next interrupt
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169 will simply turn off the Tx interrupt again. */
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173 portEXIT_CRITICAL();
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177 /*-----------------------------------------------------------*/
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180 * UART RX interrupt service routine.
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182 __interrupt void UART0_RxISR( void )
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184 volatile signed portCHAR cChar;
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185 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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187 /* Get the character from the UART and post it on the queue of Rxed
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191 xQueueSendFromISR( xRxedChars, ( const void *const ) &cChar, &xHigherPriorityTaskWoken );
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193 if( xHigherPriorityTaskWoken )
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195 /*If the post causes a task to wake force a context switch
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196 as the woken task may have a higher priority than the task we have
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198 portYIELD_FROM_ISR();
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201 /*-----------------------------------------------------------*/
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204 * UART Tx interrupt service routine.
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206 __interrupt void UART0_TxISR( void )
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208 signed portCHAR cChar;
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209 signed portBASE_TYPE xTaskWoken = pdFALSE;
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211 /* The previous character has been transmitted. See if there are any
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212 further characters waiting transmission. */
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213 if( xQueueReceiveFromISR(xCharsForTx, &cChar, &xTaskWoken) == pdTRUE )
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215 /* There was another character queued - transmit it now. */
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220 /* There were no other characters to transmit. */
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221 sTHREEmpty = pdTRUE;
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223 /* Disable transmit interrupts */
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