2 FreeRTOS.org V4.0.3 - Copyright (C) 2003-2006 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 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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30 ***************************************************************************
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34 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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37 /* Standard includes. */
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40 /* Scheduler includes. */
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41 #include "FreeRTOS.h"
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44 /* Demo application includes. */
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47 /*-----------------------------------------------------------*/
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49 /* Location of the COM0 registers. */
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50 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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52 /* Interrupt control macros. */
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53 #define serINTERRUPT_LEVEL ( 5 )
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54 #define vInterruptOn() AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )
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55 #define vInterruptOff() AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )
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57 /* Misc constants. */
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58 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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59 #define serHANDLE ( ( xComPortHandle ) 1 )
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60 #define serNO_BLOCK ( ( portTickType ) 0 )
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61 #define serNO_TIMEGUARD ( ( unsigned portLONG ) 0 )
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62 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 0 )
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65 /* Queues used to hold received characters, and characters waiting to be
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67 static xQueueHandle xRxedChars;
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68 static xQueueHandle xCharsForTx;
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70 /*-----------------------------------------------------------*/
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72 /* Interrupt entry point written in the assembler file serialISR.s79. */
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73 extern void vSerialISREntry( void );
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75 /* The interrupt service routine - called from the assembly entry point. */
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76 __arm void vSerialISR( void );
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78 /*-----------------------------------------------------------*/
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81 * See the serial2.h header file.
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83 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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85 xComPortHandle xReturn = serHANDLE;
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86 extern void ( vUART_ISR )( void );
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88 /* Create the queues used to hold Rx and Tx characters. */
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89 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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90 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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92 /* If the queues were created correctly then setup the serial port
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94 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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96 portENTER_CRITICAL();
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98 /* Enable the USART clock. */
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99 AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );
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101 AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned portLONG ) AT91C_PA5_RXD0 ) | ( ( unsigned portLONG ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );
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103 /* Set the required protocol. */
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104 AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );
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106 /* Enable Rx and Tx. */
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107 serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
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109 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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110 until there are characters to be transmitted. */
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111 AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );
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113 /* Enable the interrupts in the AIC. */
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114 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );
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115 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );
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117 portEXIT_CRITICAL();
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121 xReturn = ( xComPortHandle ) 0;
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124 /* This demo file only supports a single port but we have to return
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125 something to comply with the standard demo header file. */
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128 /*-----------------------------------------------------------*/
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130 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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132 /* The port handle is not required as this driver only supports one port. */
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135 /* Get the next character from the buffer. Return false if no characters
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136 are available, or arrive before xBlockTime expires. */
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137 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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146 /*-----------------------------------------------------------*/
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148 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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150 signed portCHAR *pxNext;
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152 /* A couple of parameters that this port does not use. */
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153 ( void ) usStringLength;
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156 /* NOTE: This implementation does not handle the queue being full as no
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157 block time is used! */
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159 /* The port handle is not required as this driver only supports UART0. */
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162 /* Send each character in the string, one at a time. */
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163 pxNext = ( signed portCHAR * ) pcString;
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166 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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170 /*-----------------------------------------------------------*/
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172 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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174 /* Place the character in the queue of characters to be transmitted. */
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175 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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180 /* Turn on the Tx interrupt so the ISR will remove the character from the
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181 queue and send it. This does not need to be in a critical section as
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182 if the interrupt has already removed the character the next interrupt
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183 will simply turn off the Tx interrupt again. */
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188 /*-----------------------------------------------------------*/
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190 void vSerialClose( xComPortHandle xPort )
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192 /* Not supported as not required by the demo application. */
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194 /*-----------------------------------------------------------*/
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196 /* Serial port ISR. This can cause a context switch so is not defined as a
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197 standard ISR using the __irq keyword. Instead a wrapper function is defined
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198 within serialISR.s79 which in turn calls this function. See the port
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199 documentation on the FreeRTOS.org website for more information. */
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200 __arm void vSerialISR( void )
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202 unsigned portLONG ulStatus;
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203 signed portCHAR cChar;
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204 portBASE_TYPE xTaskWokenByTx = pdFALSE, xTaskWokenByPost = pdFALSE;
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206 /* What caused the interrupt? */
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207 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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209 if( ulStatus & AT91C_US_TXRDY )
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211 /* The interrupt was caused by the THR becoming empty. Are there any
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212 more characters to transmit? */
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213 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWokenByTx ) == pdTRUE )
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215 /* A character was retrieved from the queue so can be sent to the
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217 serCOM0->US_THR = cChar;
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221 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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226 if( ulStatus & AT91C_US_RXRDY )
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228 /* The interrupt was caused by a character being received. Grab the
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229 character from the RHR and place it in the queue or received
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231 cChar = serCOM0->US_RHR;
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232 xTaskWokenByPost = xQueueSendFromISR( xRxedChars, &cChar, xTaskWokenByPost );
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235 /* If a task was woken by either a character being received or a character
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236 being transmitted then we may need to switch to another task. */
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237 portEND_SWITCHING_ISR( ( xTaskWokenByPost || xTaskWokenByTx ) );
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239 /* End the interrupt in the AIC. */
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240 AT91C_BASE_AIC->AIC_EOICR = 0;
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