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First version under SVN is V4.0.1
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Richard Barry
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Demo/AVR_ATMega323_WinAVR/serial/serial.c
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Demo/AVR_ATMega323_WinAVR/serial/serial.c
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/*
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FreeRTOS V4.0.1 - Copyright (C) 2003-2006 Richard Barry.
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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***************************************************************************
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*/
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/*
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Changes from V1.2.3
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+ The function xPortInitMinimal() has been renamed to
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xSerialPortInitMinimal() and the function xPortInit() has been renamed
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to xSerialPortInit().
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Changes from V2.0.0
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+ Delay periods are now specified using variables and constants of
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portTickType rather than unsigned portLONG.
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+ xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.
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Changes from V2.6.0
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+ Replaced the inb() and outb() functions with direct memory
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access. This allows the port to be built with the 20050414 build of
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WinAVR.
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*/
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/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
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#include <stdlib.h>
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#include <avr/interrupt.h>
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#include "FreeRTOS.h"
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#include "queue.h"
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#include "task.h"
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#include "serial.h"
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#define serBAUD_DIV_CONSTANT ( ( unsigned portLONG ) 16 )
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/* Constants for writing to UCSRB. */
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#define serRX_INT_ENABLE ( ( unsigned portCHAR ) 0x80 )
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#define serRX_ENABLE ( ( unsigned portCHAR ) 0x10 )
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#define serTX_ENABLE ( ( unsigned portCHAR ) 0x08 )
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#define serTX_INT_ENABLE ( ( unsigned portCHAR ) 0x20 )
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/* Constants for writing to UCSRC. */
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#define serUCSRC_SELECT ( ( unsigned portCHAR ) 0x80 )
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#define serEIGHT_DATA_BITS ( ( unsigned portCHAR ) 0x06 )
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static xQueueHandle xRxedChars;
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static xQueueHandle xCharsForTx;
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#define vInterruptOn() \
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{ \
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unsigned portCHAR ucByte; \
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\
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ucByte = UCSRB; \
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ucByte |= serTX_INT_ENABLE; \
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UCSRB = ucByte; \
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}
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/*-----------------------------------------------------------*/
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#define vInterruptOff() \
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{ \
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unsigned portCHAR ucInByte; \
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\
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ucInByte = UCSRB; \
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ucInByte &= ~serTX_INT_ENABLE; \
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UCSRB = ucInByte; \
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}
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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{
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unsigned portLONG ulBaudRateCounter;
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unsigned portCHAR ucByte;
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portENTER_CRITICAL();
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{
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/* Create the queues used by the com test task. */
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xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
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/* Calculate the baud rate register value from the equation in the
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data sheet. */
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ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned portLONG ) 1;
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/* Set the baud rate. */
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ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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UBRRL = ucByte;
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ulBaudRateCounter >>= ( unsigned portLONG ) 8;
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ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
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UBRRH = ucByte;
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/* Enable the Rx interrupt. The Tx interrupt will get enabled
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later. Also enable the Rx and Tx. */
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UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );
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/* Set the data bits to 8. */
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UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );
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}
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portEXIT_CRITICAL();
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/* Unlike other ports, this serial code does not allow for more than one
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com port. We therefore don't return a pointer to a port structure and can
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instead just return NULL. */
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return NULL;
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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{
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/* Only one port is supported. */
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( void ) pxPort;
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/* Get the next character from the buffer. Return false if no characters
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are available, or arrive before xBlockTime expires. */
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if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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{
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return pdTRUE;
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}
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else
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{
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return pdFALSE;
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}
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}
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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{
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/* Only one port is supported. */
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( void ) pxPort;
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/* Return false if after the block time there is no room on the Tx queue. */
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if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
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{
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return pdFAIL;
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}
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vInterruptOn();
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return pdPASS;
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}
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/*-----------------------------------------------------------*/
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void vSerialClose( xComPortHandle xPort )
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{
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unsigned portCHAR ucByte;
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/* The parameter is not used. */
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( void ) xPort;
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/* Turn off the interrupts. We may also want to delete the queues and/or
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re-install the original ISR. */
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portENTER_CRITICAL();
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{
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vInterruptOff();
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ucByte = UCSRB;
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ucByte &= ~serRX_INT_ENABLE;
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UCSRB = ucByte;
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}
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portEXIT_CRITICAL();
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}
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/*-----------------------------------------------------------*/
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SIGNAL( SIG_UART_RECV )
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{
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signed portCHAR cChar;
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/* Get the character and post it on the queue of Rxed characters.
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If the post causes a task to wake force a context switch as the woken task
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may have a higher priority than the task we have interrupted. */
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cChar = UDR;
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if( xQueueSendFromISR( xRxedChars, &cChar, pdFALSE ) )
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{
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taskYIELD();
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}
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}
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/*-----------------------------------------------------------*/
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SIGNAL( SIG_UART_DATA )
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{
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signed portCHAR cChar, cTaskWoken;
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if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
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{
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/* Send the next character queued for Tx. */
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UDR = cChar;
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}
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else
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{
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/* Queue empty, nothing to send. */
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vInterruptOff();
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}
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}
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