2 FreeRTOS.org V4.8.0 - Copyright (C) 2003-2008 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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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 * SAVE TIME AND MONEY! Why not get us to quote to get FreeRTOS.org *
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30 * running on your hardware - or even write all or part of your application*
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31 * for you? See http://www.OpenRTOS.com for details. *
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33 ***************************************************************************
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34 ***************************************************************************
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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 /*-----------------------------------------------------------*/
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65 /* Location of the COM0 registers. */
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66 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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68 /* Interrupt control macros. */
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69 #define serINTERRUPT_LEVEL ( 5 )
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70 #define vInterruptOn() AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )
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71 #define vInterruptOff() AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )
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73 /* Misc constants. */
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74 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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75 #define serHANDLE ( ( xComPortHandle ) 1 )
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76 #define serNO_BLOCK ( ( portTickType ) 0 )
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77 #define serNO_TIMEGUARD ( ( unsigned portLONG ) 0 )
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78 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 0 )
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81 /* Queues used to hold received characters, and characters waiting to be
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83 static xQueueHandle xRxedChars;
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84 static xQueueHandle xCharsForTx;
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86 /*-----------------------------------------------------------*/
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88 /* Interrupt entry point written in the assembler file serialISR.s79. */
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89 extern void vSerialISREntry( void );
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91 /* The interrupt service routine - called from the assembly entry point. */
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92 __arm void vSerialISR( void );
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94 /*-----------------------------------------------------------*/
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97 * See the serial2.h header file.
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99 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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101 xComPortHandle xReturn = serHANDLE;
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102 extern void ( vUART_ISR )( void );
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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 portENTER_CRITICAL();
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114 /* Enable the USART clock. */
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115 AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );
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117 AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned portLONG ) AT91C_PA5_RXD0 ) | ( ( unsigned portLONG ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );
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119 /* Set the required protocol. */
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120 AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );
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122 /* Enable Rx and Tx. */
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123 serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;
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125 /* Enable the Rx interrupts. The Tx interrupts are not enabled
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126 until there are characters to be transmitted. */
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127 AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );
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129 /* Enable the interrupts in the AIC. */
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130 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );
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131 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );
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133 portEXIT_CRITICAL();
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137 xReturn = ( xComPortHandle ) 0;
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140 /* This demo file only supports a single port but we have to return
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141 something to comply with the standard demo header file. */
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144 /*-----------------------------------------------------------*/
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146 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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148 /* The port handle is not required as this driver only supports one port. */
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151 /* Get the next character from the buffer. Return false if no characters
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152 are available, or arrive before xBlockTime expires. */
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153 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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162 /*-----------------------------------------------------------*/
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164 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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166 signed portCHAR *pxNext;
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168 /* A couple of parameters that this port does not use. */
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169 ( void ) usStringLength;
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172 /* NOTE: This implementation does not handle the queue being full as no
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173 block time is used! */
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175 /* The port handle is not required as this driver only supports UART0. */
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178 /* Send each character in the string, one at a time. */
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179 pxNext = ( signed portCHAR * ) pcString;
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182 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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186 /*-----------------------------------------------------------*/
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188 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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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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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 xTaskWokenByTx = pdFALSE, xTaskWokenByPost = 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, &xTaskWokenByTx ) == 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 xTaskWokenByPost = xQueueSendFromISR( xRxedChars, &cChar, xTaskWokenByPost );
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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( ( xTaskWokenByPost || xTaskWokenByTx ) );
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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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