2 FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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4 ***************************************************************************
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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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39 by writing to Richard Barry, contact details for whom are available on the
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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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57 ***Note*** This example uses queues to send each character into an interrupt
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58 service routine and out of an interrupt service routine individually. This
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59 is done to demonstrate queues being used in an interrupt, and to deliberately
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60 load the system to test the FreeRTOS port. It is *NOT* meant to be an
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61 example of an efficient implementation. An efficient implementation should
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62 use FIFO's or DMA if available, and only use FreeRTOS API functions when
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63 enough has been received to warrant a task being unblocked to process the
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67 /* Scheduler includes. */
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68 #include "FreeRTOS.h"
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71 #include "comtest2.h"
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73 /* Library includes. */
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74 #include "stm32l152_eval.h"
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76 /* Demo application includes. */
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78 /*-----------------------------------------------------------*/
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81 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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82 #define serNO_BLOCK ( ( portTickType ) 0 )
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84 /*-----------------------------------------------------------*/
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86 /* The queue used to hold received characters. */
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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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93 * See the serial2.h header file.
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95 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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97 USART_InitTypeDef USART_InitStructure;
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98 xComPortHandle xReturn;
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99 NVIC_InitTypeDef NVIC_InitStructure;
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101 /* Create the queues used to hold Rx/Tx characters. */
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102 xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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103 xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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105 /* If the queues were created correctly then setup the serial port
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107 if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
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109 USART_InitStructure.USART_BaudRate = ulWantedBaud;
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110 USART_InitStructure.USART_WordLength = USART_WordLength_8b;
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111 USART_InitStructure.USART_StopBits = USART_StopBits_1;
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112 USART_InitStructure.USART_Parity = USART_Parity_No;
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113 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
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114 USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
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116 /* The Eval board COM2 is being used, which in reality is the STM32
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118 STM_EVAL_COMInit( COM2, &USART_InitStructure );
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120 NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
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121 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY;
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122 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; /* Not used as 4 bits are used for the pre-emption priority. */;
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123 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
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124 NVIC_Init( &NVIC_InitStructure );
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125 USART_ITConfig( USART3, USART_IT_RXNE, ENABLE );
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129 xReturn = ( xComPortHandle ) 0;
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132 /* This demo file only supports a single port but we have to return
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133 something to comply with the standard demo header file. */
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136 /*-----------------------------------------------------------*/
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138 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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140 /* The port handle is not required as this driver only supports one port. */
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143 /* Get the next character from the buffer. Return false if no characters
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144 are available, or arrive before xBlockTime expires. */
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145 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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154 /*-----------------------------------------------------------*/
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156 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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158 signed portCHAR *pxNext;
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160 /* A couple of parameters that this port does not use. */
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161 ( void ) usStringLength;
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164 /* NOTE: This implementation does not handle the queue being full as no
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165 block time is used! */
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167 /* The port handle is not required as this driver only supports UART1. */
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170 /* Send each character in the string, one at a time. */
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171 pxNext = ( signed portCHAR * ) pcString;
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174 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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178 /*-----------------------------------------------------------*/
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180 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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182 signed portBASE_TYPE xReturn;
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184 if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS )
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187 USART_ITConfig( USART3, USART_IT_TXE, ENABLE );
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196 /*-----------------------------------------------------------*/
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198 void vSerialClose( xComPortHandle xPort )
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200 /* Not supported as not required by the demo application. */
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202 /*-----------------------------------------------------------*/
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204 void USART3_IRQHandler( void )
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206 portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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209 if( USART_GetITStatus( USART3, USART_IT_TXE ) == SET )
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211 /* The interrupt was caused by the TX register becoming empty. Are
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212 there any more characters to transmit? */
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213 if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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215 /* A character was retrieved from the queue so can be sent to the
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217 USART_SendData( USART3, cChar );
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221 USART_ITConfig( USART3, USART_IT_TXE, DISABLE );
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225 if( USART_GetITStatus( USART3, USART_IT_RXNE ) == SET )
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227 /* A character has been received on the USART, send it to the Rx
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229 cChar = USART_ReceiveData( USART3 );
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230 xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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233 /* If sending or receiving from a queue has caused a task to unblock, and
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234 the unblocked task has a priority equal to or higher than the currently
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235 running task (the task this ISR interrupted), then xHigherPriorityTaskWoken
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236 will have automatically been set to pdTRUE within the queue send or receive
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237 function. portEND_SWITCHING_ISR() will then ensure that this ISR returns
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238 directly to the higher priority unblocked task. */
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239 portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
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