2 FreeRTOS V5.4.1 - 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 * Looking for a quick start? Then check out the FreeRTOS eBook! *
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29 * See http://www.FreeRTOS.org/Documentation for details *
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31 ***************************************************************************
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35 Please ensure to read the configuration and relevant port sections of the
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36 online documentation.
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38 http://www.FreeRTOS.org - Documentation, latest information, license and
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41 http://www.SafeRTOS.com - A version that is certified for use in safety
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44 http://www.OpenRTOS.com - Commercial support, development, porting,
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45 licensing and training services.
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49 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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52 /* Standard includes. */
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55 /* Scheduler includes. */
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56 #include "FreeRTOS.h"
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59 /* Demo application includes. */
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62 /* Atmel library includes. */
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63 #include <usart/usart.h>
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64 #include <aic/aic.h>
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65 #include <pmc/pmc.h>
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67 /*-----------------------------------------------------------*/
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69 /* Location of the COM0 registers. */
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70 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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72 /* Interrupt control macros. */
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73 #define serINTERRUPT_LEVEL ( 5 )
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74 #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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75 #define vInterruptOff() serCOM0->US_IDR = AT91C_US_TXRDY
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77 /* Misc constants. */
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78 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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79 #define serHANDLE ( ( xComPortHandle ) 1 )
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80 #define serNO_BLOCK ( ( portTickType ) 0 )
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81 #define serNO_TIMEGUARD ( ( unsigned portLONG ) 0 )
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82 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 0 )
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85 /* Queues used to hold received characters, and characters waiting to be
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87 static xQueueHandle xRxedChars;
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88 static xQueueHandle xCharsForTx;
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90 /*-----------------------------------------------------------*/
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92 /* The interrupt service routine. */
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93 __arm void vSerialISR( void );
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95 /*-----------------------------------------------------------*/
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98 * See the serial2.h header file.
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100 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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102 xComPortHandle xReturn = serHANDLE;
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104 /* Create the queues used to hold Rx and Tx characters. */
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105 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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106 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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108 /* If the queues were created correctly then setup the serial port
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110 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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112 PMC_EnablePeripheral( AT91C_ID_US0 );
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113 portENTER_CRITICAL();
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115 USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
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117 /* Enable Rx and Tx. */
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118 USART_SetTransmitterEnabled( serCOM0, pdTRUE );
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119 USART_SetReceiverEnabled( serCOM0, pdTRUE );
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121 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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122 until there are characters to be transmitted. */
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123 serCOM0->US_IER = AT91C_US_RXRDY;
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125 /* Enable the interrupts in the AIC. */
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126 AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
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127 AIC_EnableIT( AT91C_ID_US0 );
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129 portEXIT_CRITICAL();
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133 xReturn = ( xComPortHandle ) 0;
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136 /* This demo file only supports a single port but we have to return
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137 something to comply with the standard demo header file. */
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140 /*-----------------------------------------------------------*/
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142 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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144 /* The port handle is not required as this driver only supports one port. */
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147 /* Get the next character from the buffer. Return false if no characters
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148 are available, or arrive before xBlockTime expires. */
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149 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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158 /*-----------------------------------------------------------*/
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160 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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162 signed portCHAR *pxNext;
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164 /* A couple of parameters that this port does not use. */
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165 ( void ) usStringLength;
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168 /* NOTE: This implementation does not handle the queue being full as no
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169 block time is used! */
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171 /* The port handle is not required as this driver only supports UART0. */
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174 /* Send each character in the string, one at a time. */
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175 pxNext = ( signed portCHAR * ) pcString;
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178 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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182 /*-----------------------------------------------------------*/
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184 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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186 /* Just to remove compiler warning. */
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189 /* Place the character in the queue of characters to be transmitted. */
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190 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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195 /* Turn on the Tx interrupt so the ISR will remove the character from the
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196 queue and send it. This does not need to be in a critical section as
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197 if the interrupt has already removed the character the next interrupt
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198 will simply turn off the Tx interrupt again. */
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203 /*-----------------------------------------------------------*/
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205 void vSerialClose( xComPortHandle xPort )
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207 /* Not supported as not required by the demo application. */
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210 /*-----------------------------------------------------------*/
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212 /* Serial port ISR. This can cause a context switch so is not defined as a
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213 standard ISR using the __irq keyword. Instead a wrapper function is defined
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214 within serialISR.s79 which in turn calls this function. See the port
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215 documentation on the FreeRTOS.org website for more information. */
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216 __arm void vSerialISR( void )
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218 unsigned portLONG ulStatus;
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219 signed portCHAR cChar;
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220 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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222 /* What caused the interrupt? */
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223 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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225 if( ulStatus & AT91C_US_TXRDY )
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227 /* The interrupt was caused by the THR becoming empty. Are there any
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228 more characters to transmit? */
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229 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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231 /* A character was retrieved from the queue so can be sent to the
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233 serCOM0->US_THR = cChar;
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237 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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242 if( ulStatus & AT91C_US_RXRDY )
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244 /* The interrupt was caused by a character being received. Grab the
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245 character from the RHR and place it in the queue or received
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247 cChar = serCOM0->US_RHR;
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248 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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251 /* If a task was woken by either a character being received or a character
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252 being transmitted then we may need to switch to another task. */
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253 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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255 /* End the interrupt in the AIC. */
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256 AT91C_BASE_AIC->AIC_EOICR = 0;
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