2 * FreeRTOS Kernel V10.0.1
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 /* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR DEMO PURPOSES */
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31 #include "FreeRTOS.h"
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36 /* Constants required to setup the serial control register. */
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37 #define ser8_BIT_MODE ( ( unsigned char ) 0x40 )
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38 #define serRX_ENABLE ( ( unsigned char ) 0x10 )
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40 /* Constants to setup the timer used to generate the baud rate. */
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41 #define serCLOCK_DIV_48 ( ( unsigned char ) 0x03 )
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42 #define serUSE_PRESCALED_CLOCK ( ( unsigned char ) 0x10 )
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43 #define ser8BIT_WITH_RELOAD ( ( unsigned char ) 0x20 )
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44 #define serSMOD ( ( unsigned char ) 0x10 )
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46 static QueueHandle_t xRxedChars;
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47 static QueueHandle_t xCharsForTx;
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49 data static unsigned portBASE_TYPE uxTxEmpty;
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51 /*-----------------------------------------------------------*/
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53 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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55 unsigned long ulReloadValue;
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56 const portFLOAT fBaudConst = ( portFLOAT ) configCPU_CLOCK_HZ * ( portFLOAT ) 2.0;
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57 unsigned char ucOriginalSFRPage;
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59 portENTER_CRITICAL();
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61 ucOriginalSFRPage = SFRPAGE;
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66 /* Create the queues used by the com test task. */
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67 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
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68 xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
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70 /* Calculate the baud rate to use timer 1. */
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71 ulReloadValue = ( unsigned long ) ( ( ( portFLOAT ) 256 - ( fBaudConst / ( portFLOAT ) ( 32 * ulWantedBaud ) ) ) + ( portFLOAT ) 0.5 );
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73 /* Set timer one for desired mode of operation. */
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75 TMOD |= ser8BIT_WITH_RELOAD;
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78 /* Set the reload and start values for the time. */
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79 TL1 = ( unsigned char ) ulReloadValue;
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80 TH1 = ( unsigned char ) ulReloadValue;
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82 /* Setup the control register for standard n, 8, 1 - variable baud rate. */
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83 SCON = ser8_BIT_MODE | serRX_ENABLE;
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85 /* Enable the serial port interrupts */
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88 /* Start the timer. */
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91 SFRPAGE = ucOriginalSFRPage;
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93 portEXIT_CRITICAL();
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95 /* Unlike some ports, this serial code does not allow for more than one
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96 com port. We therefore don't return a pointer to a port structure and can
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97 instead just return NULL. */
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100 /*-----------------------------------------------------------*/
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102 void vSerialISR( void ) interrupt 4
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105 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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107 /* 8051 port interrupt routines MUST be placed within a critical section
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108 if taskYIELD() is used within the ISR! */
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110 portENTER_CRITICAL();
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114 /* Get the character and post it on the queue of Rxed characters.
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115 If the post causes a task to wake force a context switch if the woken task
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116 has a higher priority than the task we have interrupted. */
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120 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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125 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == ( portBASE_TYPE ) pdTRUE )
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127 /* Send the next character queued for Tx. */
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132 /* Queue empty, nothing to send. */
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133 uxTxEmpty = pdTRUE;
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139 if( xHigherPriorityTaskWoken )
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144 portEXIT_CRITICAL();
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146 /*-----------------------------------------------------------*/
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148 portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t xBlockTime )
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150 /* There is only one port supported. */
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153 /* Get the next character from the buffer. Return false if no characters
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154 are available, or arrive before xBlockTime expires. */
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155 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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157 return ( portBASE_TYPE ) pdTRUE;
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161 return ( portBASE_TYPE ) pdFALSE;
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164 /*-----------------------------------------------------------*/
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166 portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t xBlockTime )
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168 portBASE_TYPE xReturn;
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170 /* There is only one port supported. */
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173 portENTER_CRITICAL();
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175 if( uxTxEmpty == pdTRUE )
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178 uxTxEmpty = pdFALSE;
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179 xReturn = ( portBASE_TYPE ) pdTRUE;
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183 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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185 if( xReturn == ( portBASE_TYPE ) pdFALSE )
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187 xReturn = ( portBASE_TYPE ) pdTRUE;
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191 portEXIT_CRITICAL();
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195 /*-----------------------------------------------------------*/
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197 void vSerialClose( xComPortHandle xPort )
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199 /* Not implemented in this port. */
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202 /*-----------------------------------------------------------*/
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