2 FreeRTOS V6.0.0 - 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 * The FreeRTOS eBook and reference manual are available to purchase for a *
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29 * small fee. Help yourself get started quickly while also helping the *
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30 * FreeRTOS project! See http://www.FreeRTOS.org/Documentation for details *
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32 ***************************************************************************
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36 Please ensure to read the configuration and relevant port sections of the
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37 online documentation.
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39 http://www.FreeRTOS.org - Documentation, latest information, license and
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42 http://www.SafeRTOS.com - A version that is certified for use in safety
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45 http://www.OpenRTOS.com - Commercial support, development, porting,
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46 licensing and training services.
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50 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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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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60 /* Demo application includes. */
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63 /* Atmel library includes. */
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64 #include <usart/usart.h>
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65 #include <aic/aic.h>
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66 #include <pmc/pmc.h>
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68 /*-----------------------------------------------------------*/
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70 /* Location of the COM0 registers. */
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71 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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73 /* Interrupt control macros. */
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74 #define serINTERRUPT_LEVEL ( 5 )
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75 #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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76 #define vInterruptOff() serCOM0->US_IDR = AT91C_US_TXRDY
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78 /* Misc constants. */
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79 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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80 #define serHANDLE ( ( xComPortHandle ) 1 )
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81 #define serNO_BLOCK ( ( portTickType ) 0 )
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82 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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83 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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86 /* Queues used to hold received characters, and characters waiting to be
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88 static xQueueHandle xRxedChars;
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89 static xQueueHandle xCharsForTx;
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91 /*-----------------------------------------------------------*/
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93 /* The interrupt service routine. */
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94 __arm void vSerialISR( void );
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96 /*-----------------------------------------------------------*/
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99 * See the serial2.h header file.
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101 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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103 xComPortHandle xReturn = serHANDLE;
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105 /* Create the queues used to hold Rx and Tx characters. */
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106 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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107 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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109 /* If the queues were created correctly then setup the serial port
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111 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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113 PMC_EnablePeripheral( AT91C_ID_US0 );
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114 portENTER_CRITICAL();
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116 USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
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118 /* Enable Rx and Tx. */
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119 USART_SetTransmitterEnabled( serCOM0, pdTRUE );
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120 USART_SetReceiverEnabled( serCOM0, pdTRUE );
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122 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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123 until there are characters to be transmitted. */
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124 serCOM0->US_IER = AT91C_US_RXRDY;
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126 /* Enable the interrupts in the AIC. */
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127 AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
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128 AIC_EnableIT( AT91C_ID_US0 );
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130 portEXIT_CRITICAL();
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134 xReturn = ( xComPortHandle ) 0;
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137 /* This demo file only supports a single port but we have to return
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138 something to comply with the standard demo header file. */
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141 /*-----------------------------------------------------------*/
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143 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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145 /* The port handle is not required as this driver only supports one port. */
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148 /* Get the next character from the buffer. Return false if no characters
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149 are available, or arrive before xBlockTime expires. */
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150 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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159 /*-----------------------------------------------------------*/
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161 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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163 signed char *pxNext;
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165 /* A couple of parameters that this port does not use. */
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166 ( void ) usStringLength;
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169 /* NOTE: This implementation does not handle the queue being full as no
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170 block time is used! */
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172 /* The port handle is not required as this driver only supports UART0. */
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175 /* Send each character in the string, one at a time. */
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176 pxNext = ( signed char * ) pcString;
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179 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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183 /*-----------------------------------------------------------*/
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185 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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187 /* Just to remove compiler warning. */
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190 /* Place the character in the queue of characters to be transmitted. */
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191 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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196 /* Turn on the Tx interrupt so the ISR will remove the character from the
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197 queue and send it. This does not need to be in a critical section as
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198 if the interrupt has already removed the character the next interrupt
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199 will simply turn off the Tx interrupt again. */
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204 /*-----------------------------------------------------------*/
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206 void vSerialClose( xComPortHandle xPort )
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208 /* Not supported as not required by the demo application. */
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211 /*-----------------------------------------------------------*/
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213 /* Serial port ISR. This can cause a context switch so is not defined as a
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214 standard ISR using the __irq keyword. Instead a wrapper function is defined
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215 within serialISR.s79 which in turn calls this function. See the port
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216 documentation on the FreeRTOS.org website for more information. */
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217 __arm void vSerialISR( void )
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219 unsigned long ulStatus;
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221 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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223 /* What caused the interrupt? */
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224 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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226 if( ulStatus & AT91C_US_TXRDY )
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228 /* The interrupt was caused by the THR becoming empty. Are there any
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229 more characters to transmit? */
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230 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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232 /* A character was retrieved from the queue so can be sent to the
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234 serCOM0->US_THR = cChar;
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238 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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243 if( ulStatus & AT91C_US_RXRDY )
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245 /* The interrupt was caused by a character being received. Grab the
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246 character from the RHR and place it in the queue or received
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248 cChar = serCOM0->US_RHR;
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249 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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252 /* If a task was woken by either a character being received or a character
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253 being transmitted then we may need to switch to another task. */
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254 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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256 /* End the interrupt in the AIC. */
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257 AT91C_BASE_AIC->AIC_EOICR = 0;
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