2 FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 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 it
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7 under the terms of the GNU General Public License (version 2) as published
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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53 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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56 /* Standard includes. */
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59 /* Scheduler includes. */
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60 #include "FreeRTOS.h"
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63 /* Demo application includes. */
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66 /* Atmel library includes. */
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67 #include <usart/usart.h>
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68 #include <aic/aic.h>
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69 #include <pmc/pmc.h>
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71 /*-----------------------------------------------------------*/
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73 /* Location of the COM0 registers. */
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74 #define serCOM0 ( ( AT91PS_USART ) AT91C_BASE_US0 )
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76 /* Interrupt control macros. */
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77 #define serINTERRUPT_LEVEL ( 5 )
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78 #define vInterruptOn() serCOM0->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )
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79 #define vInterruptOff() serCOM0->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 portLONG ) 0 )
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86 #define serNO_PERIPHERAL_B_SETUP ( ( unsigned portLONG ) 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. */
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97 __arm 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 portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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106 xComPortHandle xReturn = serHANDLE;
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108 /* Create the queues used to hold Rx and Tx characters. */
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109 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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110 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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112 /* If the queues were created correctly then setup the serial port
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114 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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116 PMC_EnablePeripheral( AT91C_ID_US0 );
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117 portENTER_CRITICAL();
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119 USART_Configure( serCOM0, ( AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE ), ulWantedBaud, configCPU_CLOCK_HZ );
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121 /* Enable Rx and Tx. */
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122 USART_SetTransmitterEnabled( serCOM0, pdTRUE );
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123 USART_SetReceiverEnabled( serCOM0, pdTRUE );
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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 serCOM0->US_IER = AT91C_US_RXRDY;
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129 /* Enable the interrupts in the AIC. */
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130 AIC_ConfigureIT( AT91C_ID_US0, AT91C_AIC_PRIOR_LOWEST, ( void (*)( void ) ) vSerialISR );
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131 AIC_EnableIT( 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 /* Just to remove compiler warning. */
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193 /* Place the character in the queue of characters to be transmitted. */
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194 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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199 /* Turn on the Tx interrupt so the ISR will remove the character from the
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200 queue and send it. This does not need to be in a critical section as
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201 if the interrupt has already removed the character the next interrupt
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202 will simply turn off the Tx interrupt again. */
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207 /*-----------------------------------------------------------*/
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209 void vSerialClose( xComPortHandle xPort )
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211 /* Not supported as not required by the demo application. */
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214 /*-----------------------------------------------------------*/
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216 /* Serial port ISR. This can cause a context switch so is not defined as a
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217 standard ISR using the __irq keyword. Instead a wrapper function is defined
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218 within serialISR.s79 which in turn calls this function. See the port
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219 documentation on the FreeRTOS.org website for more information. */
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220 __arm void vSerialISR( void )
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222 unsigned portLONG ulStatus;
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223 signed portCHAR cChar;
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224 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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226 /* What caused the interrupt? */
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227 ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;
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229 if( ulStatus & AT91C_US_TXRDY )
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231 /* The interrupt was caused by the THR becoming empty. Are there any
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232 more characters to transmit? */
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233 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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235 /* A character was retrieved from the queue so can be sent to the
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237 serCOM0->US_THR = cChar;
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241 /* Queue empty, nothing to send so turn off the Tx interrupt. */
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246 if( ulStatus & AT91C_US_RXRDY )
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248 /* The interrupt was caused by a character being received. Grab the
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249 character from the RHR and place it in the queue or received
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251 cChar = serCOM0->US_RHR;
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252 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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255 /* If a task was woken by either a character being received or a character
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256 being transmitted then we may need to switch to another task. */
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257 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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259 /* End the interrupt in the AIC. */
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260 AT91C_BASE_AIC->AIC_EOICR = 0;
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