2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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31 * This is a concise, step by step, 'hands on' guide that describes both *
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32 * general multitasking concepts and FreeRTOS specifics. It presents and *
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33 * explains numerous examples that are written using the FreeRTOS API. *
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34 * Full source code for all the examples is provided in an accompanying *
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37 ***************************************************************************
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38 ***************************************************************************
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40 Please ensure to read the configuration and relevant port sections of the
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41 online documentation.
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43 http://www.FreeRTOS.org - Documentation, latest information, license and
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46 http://www.SafeRTOS.com - A version that is certified for use in safety
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49 http://www.OpenRTOS.com - Commercial support, development, porting,
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50 licensing and training services.
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56 + Made serial ISR handling more complete and robust.
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60 + Split serial.c into serial.c and serialISR.c. serial.c can be
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61 compiled using ARM or THUMB modes. serialISR.c must always be
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62 compiled in ARM mode.
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63 + Another small change to cSerialPutChar().
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67 + In cSerialPutChar() an extra check is made to ensure the post to
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68 the queue was successful if then attempting to retrieve the posted
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74 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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76 This file contains all the serial port components that can be compiled to
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77 either ARM or THUMB mode. Components that must be compiled to ARM mode are
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78 contained in serialISR.c.
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81 /* Standard includes. */
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84 /* Scheduler includes. */
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85 #include "FreeRTOS.h"
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89 /* Demo application includes. */
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92 /*-----------------------------------------------------------*/
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94 /* Constants to setup and access the UART. */
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95 #define serDLAB ( ( unsigned portCHAR ) 0x80 )
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96 #define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
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97 #define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
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98 #define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
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99 #define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
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100 #define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
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101 #define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
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102 #define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
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104 /* Constants to setup and access the VIC. */
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105 #define serUART0_VIC_CHANNEL ( ( unsigned portLONG ) 0x0006 )
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106 #define serUART0_VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0040 )
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107 #define serUART0_VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
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108 #define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
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110 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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111 #define serHANDLE ( ( xComPortHandle ) 1 )
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112 #define serNO_BLOCK ( ( portTickType ) 0 )
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114 /*-----------------------------------------------------------*/
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116 /* Queues used to hold received characters, and characters waiting to be
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118 static xQueueHandle xRxedChars;
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119 static xQueueHandle xCharsForTx;
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121 /*-----------------------------------------------------------*/
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123 /* Communication flag between the interrupt service routine and serial API. */
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124 static volatile portLONG *plTHREEmpty;
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127 * The queues are created in serialISR.c as they are used from the ISR.
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128 * Obtain references to the queues and THRE Empty flag.
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130 extern void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, portLONG volatile **pplTHREEmptyFlag );
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132 /*-----------------------------------------------------------*/
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134 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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136 unsigned portLONG ulDivisor, ulWantedClock;
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137 xComPortHandle xReturn = serHANDLE;
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138 extern void ( vUART_ISR_Wrapper )( void );
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140 /* The queues are used in the serial ISR routine, so are created from
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141 serialISR.c (which is always compiled to ARM mode. */
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142 vSerialISRCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx, &plTHREEmpty );
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145 ( xRxedChars != serINVALID_QUEUE ) &&
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146 ( xCharsForTx != serINVALID_QUEUE ) &&
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147 ( ulWantedBaud != ( unsigned portLONG ) 0 )
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150 portENTER_CRITICAL();
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152 /* Setup the baud rate: Calculate the divisor value. */
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153 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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154 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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156 /* Set the DLAB bit so we can access the divisor. */
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157 UART0_LCR |= serDLAB;
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159 /* Setup the divisor. */
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160 UART0_DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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162 UART0_DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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164 /* Turn on the FIFO's and clear the buffers. */
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165 UART0_FCR = ( serFIFO_ON | serCLEAR_FIFO );
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167 /* Setup transmission format. */
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168 UART0_LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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170 /* Setup the VIC for the UART. */
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171 VICIntSelect &= ~( serUART0_VIC_CHANNEL_BIT );
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172 VICIntEnable |= serUART0_VIC_CHANNEL_BIT;
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173 VICVectAddr1 = ( portLONG ) vUART_ISR_Wrapper;
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174 VICVectCntl1 = serUART0_VIC_CHANNEL | serUART0_VIC_ENABLE;
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176 /* Enable UART0 interrupts. */
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177 UART0_IER |= serENABLE_INTERRUPTS;
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179 portEXIT_CRITICAL();
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183 xReturn = ( xComPortHandle ) 0;
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188 /*-----------------------------------------------------------*/
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190 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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192 /* The port handle is not required as this driver only supports UART0. */
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195 /* Get the next character from the buffer. Return false if no characters
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196 are available, or arrive before xBlockTime expires. */
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197 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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206 /*-----------------------------------------------------------*/
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208 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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210 signed portCHAR *pxNext;
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212 /* NOTE: This implementation does not handle the queue being full as no
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213 block time is used! */
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215 /* The port handle is not required as this driver only supports UART0. */
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217 ( void ) usStringLength;
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219 /* Send each character in the string, one at a time. */
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220 pxNext = ( signed portCHAR * ) pcString;
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223 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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227 /*-----------------------------------------------------------*/
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229 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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231 signed portBASE_TYPE xReturn;
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233 /* This demo driver only supports one port so the parameter is not used. */
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236 portENTER_CRITICAL();
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238 /* Is there space to write directly to the UART? */
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239 if( *plTHREEmpty == ( portLONG ) pdTRUE )
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241 /* We wrote the character directly to the UART, so was
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243 *plTHREEmpty = pdFALSE;
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244 UART0_THR = cOutChar;
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249 /* We cannot write directly to the UART, so queue the character.
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250 Block for a maximum of xBlockTime if there is no space in the
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252 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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254 /* Depending on queue sizing and task prioritisation: While we
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255 were blocked waiting to post interrupts were not disabled. It is
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256 possible that the serial ISR has emptied the Tx queue, in which
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257 case we need to start the Tx off again. */
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258 if( ( *plTHREEmpty == ( portLONG ) pdTRUE ) && ( xReturn == pdPASS ) )
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260 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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261 *plTHREEmpty = pdFALSE;
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262 UART0_THR = cOutChar;
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266 portEXIT_CRITICAL();
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270 /*-----------------------------------------------------------*/
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272 void vSerialClose( xComPortHandle xPort )
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274 /* Not supported as not required by the demo application. */
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277 /*-----------------------------------------------------------*/
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