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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54 * This demo application creates six co-routines and two tasks (three including
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55 * the idle task). The co-routines execute as part of the idle task hook.
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57 * Five of the created co-routines are the standard 'co-routine flash'
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58 * co-routines contained within the Demo/Common/Minimal/crflash.c file and
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59 * documented on the FreeRTOS.org WEB site.
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61 * The 'LCD Task' rotates a string on the LCD, delaying between each character
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62 * as necessitated by the slow interface, and delaying between each string just
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63 * long enough to enable the text to be read.
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65 * The sixth co-routine and final task control the transmission and reception
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66 * of a string to UART 0. The co-routine periodically sends the first
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67 * character of the string to the UART, with the UART's TxEnd interrupt being
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68 * used to transmit the remaining characters. The UART's RxEnd interrupt
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69 * receives the characters and places them on a queue to be processed by the
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70 * 'COMs Rx' task. An error is latched should an unexpected character be
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71 * received, or any character be received out of sequence.
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73 * A loopback connector is required to ensure that each character transmitted
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74 * on the UART is also received on the same UART. For test purposes the UART
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75 * FIFO's are not utalised in order to maximise the interrupt overhead. Also
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76 * a pseudo random interval is used between the start of each transmission in
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77 * order that the resultant interrupts are more randomly distributed and
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78 * therefore more likely to highlight any problems.
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80 * The flash co-routines control LED's zero to four. LED five is toggled each
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81 * time the string is transmitted on the UART. LED six is toggled each time
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82 * the string is CORRECTLY received on the UART. LED seven is latched on should
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83 * an error be detected in any task or co-routine.
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85 * In addition the idle task makes repetative calls to
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86 * prvSetAndCheckRegisters(). This simply loads the general purpose registers
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87 * with a known value, then checks each register to ensure the held value is
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88 * still correct. As a low priority task this checking routine is likely to
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89 * get repeatedly swapped in and out. A register being found to contain an
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90 * incorrect value is therefore indicative of an error in the task switching
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95 /* Scheduler include files. */
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96 #include "FreeRTOS.h"
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99 #include "croutine.h"
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101 /* Demo application include files. */
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102 #include "partest.h"
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103 #include "crflash.h"
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105 /* Library include files. */
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106 #include "DriverLib.h"
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108 /* The time to delay between writing each character to the LCD. */
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109 #define mainCHAR_WRITE_DELAY ( 2 / portTICK_RATE_MS )
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111 /* The time to delay between writing each string to the LCD. */
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112 #define mainSTRING_WRITE_DELAY ( 400 / portTICK_RATE_MS )
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114 /* The number of flash co-routines to create. */
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115 #define mainNUM_FLASH_CO_ROUTINES ( 5 )
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117 /* The length of the queue used to pass received characters to the Comms Rx
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119 #define mainRX_QUEUE_LEN ( 5 )
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121 /* The priority of the co-routine used to initiate the transmission of the
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122 string on UART 0. */
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123 #define mainTX_CO_ROUTINE_PRIORITY ( 1 )
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125 /* Only one co-routine is created so its index is not important. */
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126 #define mainTX_CO_ROUTINE_INDEX ( 0 )
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128 /* The time between transmissions of the string on UART 0. This is pseudo
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129 random in order to generate a bit or randomness to when the interrupts occur.*/
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130 #define mainMIN_TX_DELAY ( 40 / portTICK_RATE_MS )
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131 #define mainMAX_TX_DELAY ( ( portTickType ) 0x7f )
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132 #define mainOFFSET_TIME ( ( portTickType ) 3 )
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134 /* The time the Comms Rx task should wait to receive a character. This should
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135 be slightly longer than the time between transmissions. If we do not receive
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136 a character after this time then there must be an error in the transmission or
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137 the timing of the transmission. */
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138 #define mainCOMMS_RX_DELAY ( mainMAX_TX_DELAY + 20 )
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140 /* The task priorites. */
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141 #define mainLCD_TASK_PRIORITY ( tskIDLE_PRIORITY )
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142 #define mainCOMMS_RX_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 )
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144 /* The LED's toggled by the various tasks. */
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145 #define mainCOMMS_FAIL_LED ( 7 )
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146 #define mainCOMMS_RX_LED ( 6 )
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147 #define mainCOMMS_TX_LED ( 5 )
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149 /* The baud rate used by the UART comms tasks/co-routine. */
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150 #define mainBAUD_RATE ( 57600 )
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152 /* FIFO setting for the UART. The FIFO is not used to create a better test. */
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153 #define mainFIFO_SET ( 0x10 )
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155 /* The string that is transmitted on the UART contains sequentially the
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156 characters from mainFIRST_TX_CHAR to mainLAST_TX_CHAR. */
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157 #define mainFIRST_TX_CHAR '0'
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158 #define mainLAST_TX_CHAR 'z'
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160 /* Just used to walk through the program memory in order that some random data
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161 can be generated. */
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162 #define mainTOTAL_PROGRAM_MEMORY ( ( unsigned portLONG * ) ( 8 * 1024 ) )
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163 #define mainFIRST_PROGRAM_BYTES ( ( unsigned portLONG * ) 4 )
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165 /* The error routine that is called if the driver library encounters an error. */
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168 __error__(char *pcFilename, unsigned long ulLine)
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173 /*-----------------------------------------------------------*/
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176 * The task that rotates text on the LCD.
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178 static void vLCDTask( void * pvParameters );
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181 * The task that receives the characters from UART 0.
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183 static void vCommsRxTask( void * pvParameters );
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186 * The co-routine that periodically initiates the transmission of the string on
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189 static void vSerialTxCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex );
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192 * Writes a string the the LCD.
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194 static void prvWriteString( const portCHAR *pcString );
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197 * Initialisation routine for the UART.
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199 static void vSerialInit( void );
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202 * Thread safe write to the PDC.
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204 static void prvPDCWrite( portCHAR cAddress, portCHAR cData );
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207 * Function to simply set a known value into the general purpose registers
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208 * then read them back to ensure they remain set correctly. An incorrect value
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209 * being indicative of an error in the task switching mechanism.
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211 void prvSetAndCheckRegisters( void );
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214 * Latch the LED that indicates that an error has occurred.
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216 void vSetErrorLED( void );
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219 * Sets up the PLL and ports used by the demo.
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221 static void prvSetupHardware( void );
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223 /*-----------------------------------------------------------*/
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225 /* Error flag set to pdFAIL if an error is encountered in the tasks/co-routines
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226 defined within this file. */
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227 unsigned portBASE_TYPE uxErrorStatus = pdPASS;
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229 /* The next character to transmit. */
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230 static portCHAR cNextChar;
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232 /* The queue used to transmit characters from the interrupt to the Comms Rx
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234 static xQueueHandle xCommsQueue;
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236 /*-----------------------------------------------------------*/
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240 /* Create the queue used to communicate between the UART ISR and the Comms
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242 xCommsQueue = xQueueCreate( mainRX_QUEUE_LEN, sizeof( portCHAR ) );
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244 /* Setup the ports used by the demo and the clock. */
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245 prvSetupHardware();
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247 /* Create the co-routines that flash the LED's. */
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248 vStartFlashCoRoutines( mainNUM_FLASH_CO_ROUTINES );
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250 /* Create the co-routine that initiates the transmission of characters
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252 xCoRoutineCreate( vSerialTxCoRoutine, mainTX_CO_ROUTINE_PRIORITY, mainTX_CO_ROUTINE_INDEX );
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254 /* Create the LCD and Comms Rx tasks. */
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255 xTaskCreate( vLCDTask, "LCD", configMINIMAL_STACK_SIZE, NULL, mainLCD_TASK_PRIORITY, NULL );
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256 xTaskCreate( vCommsRxTask, "CMS", configMINIMAL_STACK_SIZE, NULL, mainCOMMS_RX_TASK_PRIORITY, NULL );
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258 /* Start the scheduler running the tasks and co-routines just created. */
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259 vTaskStartScheduler();
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261 /* Should not get here unless we did not have enough memory to start the
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265 /*-----------------------------------------------------------*/
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267 static void prvSetupHardware( void )
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269 /* Setup the PLL. */
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270 SysCtlClockSet( SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_6MHZ );
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272 /* Initialise the hardware used to talk to the LCD, LED's and UART. */
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274 vParTestInitialise();
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277 /*-----------------------------------------------------------*/
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279 void vApplicationIdleHook( void )
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281 /* The co-routines are executed in the idle task using the idle task
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285 /* Schedule the co-routines. */
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286 vCoRoutineSchedule();
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288 /* Run the register check function between each co-routine. */
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289 prvSetAndCheckRegisters();
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292 /*-----------------------------------------------------------*/
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294 static void prvWriteString( const portCHAR *pcString )
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296 /* Write pcString to the LED, pausing between each character. */
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297 prvPDCWrite(PDC_LCD_CSR, LCD_CLEAR);
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300 vTaskDelay( mainCHAR_WRITE_DELAY );
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301 prvPDCWrite( PDC_LCD_RAM, *pcString );
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305 /*-----------------------------------------------------------*/
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307 void vLCDTask( void * pvParameters )
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309 unsigned portBASE_TYPE uxIndex;
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310 const unsigned portCHAR ucCFGData[] = {
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311 0x30, /* Set data bus to 8-bits. */
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314 0x3C, /* Number of lines/font. */
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315 0x08, /* Display off. */
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316 0x01, /* Display clear. */
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317 0x06, /* Entry mode [cursor dir][shift]. */
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318 0x0C /* Display on [display on][curson on][blinking on]. */
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321 /* The strings that are written to the LCD. */
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322 const portCHAR *pcStringsToDisplay[] = {
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326 "www.FreeRTOS.org",
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330 /* Configure the LCD. */
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332 while( uxIndex < sizeof( ucCFGData ) )
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334 prvPDCWrite( PDC_LCD_CSR, ucCFGData[ uxIndex ] );
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336 vTaskDelay( mainCHAR_WRITE_DELAY );
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339 /* Turn the LCD Backlight on. */
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340 prvPDCWrite( PDC_CSR, 0x01 );
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342 /* Clear display. */
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343 vTaskDelay( mainCHAR_WRITE_DELAY );
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344 prvPDCWrite( PDC_LCD_CSR, LCD_CLEAR );
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349 /* Display the string on the LCD. */
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350 prvWriteString( pcStringsToDisplay[ uxIndex ] );
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352 /* Move on to the next string - wrapping if necessary. */
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354 if( *( pcStringsToDisplay[ uxIndex ] ) == 0x00 )
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357 /* Longer pause on the last string to be sent. */
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358 vTaskDelay( mainSTRING_WRITE_DELAY * 2 );
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361 /* Wait until it is time to move onto the next string. */
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362 vTaskDelay( mainSTRING_WRITE_DELAY );
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365 /*-----------------------------------------------------------*/
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367 static void vCommsRxTask( void * pvParameters )
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369 static portCHAR cRxedChar, cExpectedChar;
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371 /* Set the char we expect to receive to the start of the string. */
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372 cExpectedChar = mainFIRST_TX_CHAR;
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376 /* Wait for a character to be received. */
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377 xQueueReceive( xCommsQueue, ( void * ) &cRxedChar, mainCOMMS_RX_DELAY );
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379 /* Was the character recived (if any) the expected character. */
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380 if( cRxedChar != cExpectedChar )
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382 /* Got an unexpected character. This can sometimes occur when
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383 reseting the system using the debugger leaving characters already
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384 in the UART regsters. */
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385 uxErrorStatus = pdFAIL;
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387 /* Resync by waiting for the end of the current string. */
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388 while( cRxedChar != mainLAST_TX_CHAR )
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390 while( !xQueueReceive( xCommsQueue, ( void * ) &cRxedChar, portMAX_DELAY ) );
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393 /* The next expected character is the start of the string again. */
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394 cExpectedChar = mainFIRST_TX_CHAR;
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398 if( cExpectedChar == mainLAST_TX_CHAR )
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400 /* We have reached the end of the string - we now expect to
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401 receive the first character in the string again. The LED is
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402 toggled to indicate that the entire string was received without
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404 vParTestToggleLED( mainCOMMS_RX_LED );
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405 cExpectedChar = mainFIRST_TX_CHAR;
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409 /* We got the expected character, we now expect to receive the
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410 next character in the string. */
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416 /*-----------------------------------------------------------*/
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418 static void vSerialTxCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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420 portTickType xDelayPeriod;
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421 static unsigned portLONG *pulRandomBytes = mainFIRST_PROGRAM_BYTES;
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423 /* Co-routine MUST start with a call to crSTART. */
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424 crSTART( xHandle );
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428 /* Was the previously transmitted string received correctly? */
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429 if( uxErrorStatus != pdPASS )
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431 /* An error was encountered so set the error LED. */
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435 /* The next character to Tx is the first in the string. */
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436 cNextChar = mainFIRST_TX_CHAR;
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438 UARTIntDisable( UART0_BASE, UART_INT_TX );
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440 /* Send the first character. */
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441 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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443 HWREG( UART0_BASE + UART_O_DR ) = cNextChar;
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446 /* Move the variable to the char to Tx on so the ISR transmits
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447 the next character in the string once this one has completed. */
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450 UARTIntEnable(UART0_BASE, UART_INT_TX);
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452 /* Toggle the LED to show a new string is being transmitted. */
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453 vParTestToggleLED( mainCOMMS_TX_LED );
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455 /* Delay before we start the string off again. A pseudo-random delay
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456 is used as this will provide a better test. */
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457 xDelayPeriod = xTaskGetTickCount() + ( *pulRandomBytes );
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460 if( pulRandomBytes > mainTOTAL_PROGRAM_MEMORY )
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462 pulRandomBytes = mainFIRST_PROGRAM_BYTES;
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465 /* Make sure we don't wait too long... */
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466 xDelayPeriod &= mainMAX_TX_DELAY;
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468 /* ...but we do want to wait. */
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469 if( xDelayPeriod < mainMIN_TX_DELAY )
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471 xDelayPeriod = mainMIN_TX_DELAY;
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474 /* Block for the random(ish) time. */
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475 crDELAY( xHandle, xDelayPeriod );
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478 /* Co-routine MUST end with a call to crEND. */
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481 /*-----------------------------------------------------------*/
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483 static void vSerialInit( void )
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485 /* Enable the UART. GPIOA has already been initialised. */
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486 SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
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488 /* Set GPIO A0 and A1 as peripheral function. They are used to output the
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490 GPIODirModeSet( GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1, GPIO_DIR_MODE_HW );
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492 /* Configure the UART for 8-N-1 operation. */
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493 UARTConfigSet( UART0_BASE, mainBAUD_RATE, UART_CONFIG_WLEN_8 | UART_CONFIG_PAR_NONE | UART_CONFIG_STOP_ONE );
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495 /* We dont want to use the fifo. This is for test purposes to generate
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496 as many interrupts as possible. */
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497 HWREG( UART0_BASE + UART_O_LCR_H ) &= ~mainFIFO_SET;
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499 /* Enable both Rx and Tx interrupts. */
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500 HWREG( UART0_BASE + UART_O_IM ) |= ( UART_INT_TX | UART_INT_RX );
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501 IntEnable( INT_UART0 );
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503 /*-----------------------------------------------------------*/
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505 void vUART_ISR(void)
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507 unsigned portLONG ulStatus;
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508 portCHAR cRxedChar;
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509 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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511 /* What caused the interrupt. */
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512 ulStatus = UARTIntStatus( UART0_BASE, pdTRUE );
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514 /* Clear the interrupt. */
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515 UARTIntClear( UART0_BASE, ulStatus );
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517 /* Was an Rx interrpt pending? */
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518 if( ulStatus & UART_INT_RX )
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520 if( ( HWREG(UART0_BASE + UART_O_FR ) & UART_FR_RXFF ) )
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522 /* Get the char from the buffer and post it onto the queue of
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523 Rxed chars. Posting the character should wake the task that is
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524 blocked on the queue waiting for characters. */
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525 cRxedChar = ( portCHAR ) HWREG( UART0_BASE + UART_O_DR );
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526 xQueueSendFromISR( xCommsQueue, &cRxedChar, &xHigherPriorityTaskWoken );
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530 /* Was a Tx interrupt pending? */
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531 if( ulStatus & UART_INT_TX )
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533 /* Send the next character in the string. We are not using the FIFO. */
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534 if( cNextChar <= mainLAST_TX_CHAR )
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536 if( !( HWREG( UART0_BASE + UART_O_FR ) & UART_FR_TXFF ) )
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538 HWREG( UART0_BASE + UART_O_DR ) = cNextChar;
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544 /* If a task was woken by the character being received then we force
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545 a context switch to occur in case the task is of higher priority than
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546 the currently executing task (i.e. the task that this interrupt
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548 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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550 /*-----------------------------------------------------------*/
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552 static void prvPDCWrite( portCHAR cAddress, portCHAR cData )
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556 PDCWrite( cAddress, cData );
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560 /*-----------------------------------------------------------*/
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562 void vSetErrorLED( void )
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564 vParTestSetLED( mainCOMMS_FAIL_LED, pdTRUE );
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566 /*-----------------------------------------------------------*/
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568 void prvSetAndCheckRegisters( void )
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570 /* Fill the general purpose registers with known values. */
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571 __asm volatile( " mov r11, #10\n"
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572 " add r0, r11, #1\n"
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573 " add r1, r11, #2\n"
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574 " add r2, r11, #3\n"
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575 " add r3, r11, #4\n"
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576 " add r4, r11, #5\n"
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577 " add r5, r11, #6\n"
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578 " add r6, r11, #7\n"
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579 " add r7, r11, #8\n"
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580 " add r8, r11, #9\n"
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581 " add r9, r11, #10\n"
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582 " add r10, r11, #11\n"
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583 " add r12, r11, #12" );
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585 /* Check the values are as expected. */
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586 __asm volatile( " cmp r11, #10\n"
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587 " bne set_error_led\n"
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589 " bne set_error_led\n"
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591 " bne set_error_led\n"
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593 " bne set_error_led\n"
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595 " bne set_error_led\n"
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597 " bne set_error_led\n"
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599 " bne set_error_led\n"
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601 " bne set_error_led\n"
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603 " bne set_error_led\n"
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605 " bne set_error_led\n"
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607 " bne set_error_led\n"
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609 " bne set_error_led\n"
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611 " bne set_error_led\n"
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614 __asm volatile( "set_error_led:\n"
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616 " ldr r1, =vSetErrorLED\n"
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621 /*-----------------------------------------------------------*/
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