2 FreeRTOS V6.0.1 - Copyright (C) 2009 Real Time Engineers Ltd.
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4 ***************************************************************************
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23 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 ***NOTE*** The exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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51 licensing and training services.
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55 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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58 /* Standard includes. */
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61 /* Scheduler includes. */
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62 #include "FreeRTOS.h"
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65 /* Demo application includes. */
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68 /* Library includes. */
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69 #include "usart/usart.h"
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70 #include "pmc/pmc.h"
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71 #include "irq/irq.h"
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72 #include "pio/pio.h"
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74 /*-----------------------------------------------------------*/
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76 /* Interrupt control macros. */
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77 #define serINTERRUPT_LEVEL ( 5 )
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78 #define vInterruptOn() BOARD_USART_BASE->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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79 #define vInterruptOff() BOARD_USART_BASE->US_IDR = AT91C_US_TXRDY
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81 /* Misc constants. */
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82 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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83 #define serHANDLE ( ( xComPortHandle ) 1 )
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84 #define serNO_BLOCK ( ( portTickType ) 0 )
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85 #define serNO_TIMEGUARD ( ( unsigned long ) 0 )
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86 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned long ) 0 )
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89 /* Queues used to hold received characters, and characters waiting to be
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91 static xQueueHandle xRxedChars;
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92 static xQueueHandle xCharsForTx;
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94 /*-----------------------------------------------------------*/
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96 /* The interrupt service routine - called from the assembly entry point. */
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97 void vSerialISR( void );
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99 /*-----------------------------------------------------------*/
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102 * See the serial2.h header file.
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104 xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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106 xComPortHandle xReturn = serHANDLE;
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107 extern void ( vUART_ISR )( void );
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108 const Pin xUSART_Pins[] = { BOARD_PIN_USART_RXD, BOARD_PIN_USART_TXD };
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111 /* Create the queues used to hold Rx and Tx characters. */
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112 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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113 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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115 /* If the queues were created correctly then setup the serial port
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117 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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119 portENTER_CRITICAL();
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121 /* Enable the peripheral clock in the PMC. */
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122 PMC_EnablePeripheral( BOARD_ID_USART );
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124 /* Configure the USART. */
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125 USART_Configure( BOARD_USART_BASE, AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE | AT91C_US_NBSTOP_1_BIT, ulWantedBaud, configCPU_CLOCK_HZ );
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127 /* Configure the interrupt. Note the pre-emption priority is set
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128 in bits [8:15] of the priority value passed as the parameter. */
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129 IRQ_ConfigureIT( BOARD_ID_USART, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 8 ), vSerialISR );
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130 IRQ_EnableIT( BOARD_ID_USART );
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132 /* Enable receiver & transmitter. */
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133 USART_SetTransmitterEnabled( BOARD_USART_BASE, pdTRUE );
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134 USART_SetReceiverEnabled( BOARD_USART_BASE, pdTRUE );
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136 /* Configure IO for USART use. */
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137 PIO_Configure( xUSART_Pins, PIO_LISTSIZE( xUSART_Pins ) );
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139 portEXIT_CRITICAL();
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143 xReturn = ( xComPortHandle ) 0;
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146 /* This demo file only supports a single port but we have to return
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147 something to comply with the standard demo header file. */
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150 /*-----------------------------------------------------------*/
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152 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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154 /* The port handle is not required as this driver only supports one port. */
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157 /* Get the next character from the buffer. Return false if no characters
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158 are available, or arrive before xBlockTime expires. */
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159 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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168 /*-----------------------------------------------------------*/
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170 void vSerialPutString( xComPortHandle pxPort, const signed char * const pcString, unsigned short usStringLength )
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172 signed char *pxNext;
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174 /* A couple of parameters that this port does not use. */
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175 ( void ) usStringLength;
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178 /* NOTE: This implementation does not handle the queue being full as no
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179 block time is used! */
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181 /* The port handle is not required as this driver only supports UART0. */
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184 /* Send each character in the string, one at a time. */
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185 pxNext = ( signed char * ) pcString;
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188 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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192 /*-----------------------------------------------------------*/
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194 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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196 /* Place the character in the queue of characters to be transmitted. */
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197 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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202 /* Turn on the Tx interrupt so the ISR will remove the character from the
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203 queue and send it. This does not need to be in a critical section as
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204 if the interrupt has already removed the character the next interrupt
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205 will simply turn off the Tx interrupt again. */
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210 /*-----------------------------------------------------------*/
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212 void vSerialClose( xComPortHandle xPort )
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214 /* Not supported as not required by the demo application. */
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216 /*-----------------------------------------------------------*/
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218 void vSerialISR( void )
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220 unsigned long ulStatus;
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222 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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224 /* What caused the interrupt? */
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225 ulStatus = BOARD_USART_BASE->US_CSR &= BOARD_USART_BASE->US_IMR;
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227 if( ulStatus & AT91C_US_TXRDY )
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229 /* The interrupt was caused by the THR becoming empty. Are there any
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230 more characters to transmit? */
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231 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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233 /* A character was retrieved from the queue so can be sent to the
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235 BOARD_USART_BASE->US_THR = cChar;
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239 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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244 if( ulStatus & AT91C_US_RXRDY )
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246 /* The interrupt was caused by a character being received. Grab the
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247 character from the RHR and place it in the queue or received
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249 cChar = BOARD_USART_BASE->US_RHR;
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250 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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253 /* If a task was woken by either a character being received or a character
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254 being transmitted then we may need to switch to another task. */
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255 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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