2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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14 GNU General Public License for more details.
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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57 /* Standard includes. */
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60 /* Scheduler includes. */
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61 #include "FreeRTOS.h"
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64 /* Demo application includes. */
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67 /* Atmel library includes. */
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68 #include <usart/usart.h>
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69 #include <aic/aic.h>
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70 #include <pmc/pmc.h>
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72 /*-----------------------------------------------------------*/
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74 /* Location of the COM0 registers. */
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75 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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77 /* Interrupt control macros. */
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78 #define serINTERRUPT_LEVEL ( 5 )
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79 #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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80 #define vInterruptOff() serCOM0->US_IDR = AT91C_US_TXRDY
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82 /* Misc constants. */
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83 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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84 #define serHANDLE ( ( xComPortHandle ) 1 )
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85 #define serNO_BLOCK ( ( portTickType ) 0 )
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86 #define serNO_TIMEGUARD ( ( unsigned portLONG ) 0 )
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87 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 0 )
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90 /* Queues used to hold received characters, and characters waiting to be
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92 static xQueueHandle xRxedChars;
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93 static xQueueHandle xCharsForTx;
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95 /*-----------------------------------------------------------*/
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97 /* The interrupt service routine. */
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98 __arm void vSerialISR( void );
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100 /*-----------------------------------------------------------*/
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103 * See the serial2.h header file.
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105 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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107 xComPortHandle xReturn = serHANDLE;
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109 /* Create the queues used to hold Rx and Tx characters. */
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110 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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111 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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113 /* If the queues were created correctly then setup the serial port
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115 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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117 PMC_EnablePeripheral( AT91C_ID_US0 );
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118 portENTER_CRITICAL();
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120 USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
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122 /* Enable Rx and Tx. */
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123 USART_SetTransmitterEnabled( serCOM0, pdTRUE );
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124 USART_SetReceiverEnabled( serCOM0, pdTRUE );
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126 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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127 until there are characters to be transmitted. */
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128 serCOM0->US_IER = AT91C_US_RXRDY;
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130 /* Enable the interrupts in the AIC. */
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131 AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
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132 AIC_EnableIT( AT91C_ID_US0 );
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134 portEXIT_CRITICAL();
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138 xReturn = ( xComPortHandle ) 0;
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141 /* This demo file only supports a single port but we have to return
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142 something to comply with the standard demo header file. */
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145 /*-----------------------------------------------------------*/
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147 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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149 /* The port handle is not required as this driver only supports one port. */
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152 /* Get the next character from the buffer. Return false if no characters
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153 are available, or arrive before xBlockTime expires. */
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154 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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163 /*-----------------------------------------------------------*/
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165 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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167 signed portCHAR *pxNext;
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169 /* A couple of parameters that this port does not use. */
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170 ( void ) usStringLength;
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173 /* NOTE: This implementation does not handle the queue being full as no
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174 block time is used! */
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176 /* The port handle is not required as this driver only supports UART0. */
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179 /* Send each character in the string, one at a time. */
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180 pxNext = ( signed portCHAR * ) pcString;
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183 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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187 /*-----------------------------------------------------------*/
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189 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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191 /* Just to remove compiler warning. */
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194 /* Place the character in the queue of characters to be transmitted. */
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195 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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200 /* Turn on the Tx interrupt so the ISR will remove the character from the
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201 queue and send it. This does not need to be in a critical section as
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202 if the interrupt has already removed the character the next interrupt
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203 will simply turn off the Tx interrupt again. */
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208 /*-----------------------------------------------------------*/
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210 void vSerialClose( xComPortHandle xPort )
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212 /* Not supported as not required by the demo application. */
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215 /*-----------------------------------------------------------*/
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217 /* Serial port ISR. This can cause a context switch so is not defined as a
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218 standard ISR using the __irq keyword. Instead a wrapper function is defined
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219 within serialISR.s79 which in turn calls this function. See the port
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220 documentation on the FreeRTOS.org website for more information. */
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221 __arm void vSerialISR( void )
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223 unsigned portLONG ulStatus;
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224 signed portCHAR cChar;
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225 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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227 /* What caused the interrupt? */
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228 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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230 if( ulStatus & AT91C_US_TXRDY )
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232 /* The interrupt was caused by the THR becoming empty. Are there any
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233 more characters to transmit? */
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234 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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236 /* A character was retrieved from the queue so can be sent to the
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238 serCOM0->US_THR = cChar;
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242 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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247 if( ulStatus & AT91C_US_RXRDY )
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249 /* The interrupt was caused by a character being received. Grab the
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250 character from the RHR and place it in the queue or received
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252 cChar = serCOM0->US_RHR;
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253 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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256 /* If a task was woken by either a character being received or a character
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257 being transmitted then we may need to switch to another task. */
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258 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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260 /* End the interrupt in the AIC. */
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261 AT91C_BASE_AIC->AIC_EOICR = 0;
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