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/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
http://www.FreeRTOS.org - Documentation, latest information, license and
contact details.
http://www.SafeRTOS.com - A version that is certified for use in safety
critical systems.
http://www.OpenRTOS.com - Commercial support, development, porting,
licensing and training services.
*/
/*
Changes from V1.2.3
+ The function xPortInitMinimal() has been renamed to
xSerialPortInitMinimal() and the function xPortInit() has been renamed
to xSerialPortInit().
Changes from V2.0.0
+ Delay periods are now specified using variables and constants of
portTickType rather than unsigned portLONG.
+ xQueueReceiveFromISR() used in place of xQueueReceive() within the ISR.
Changes from V2.6.0
+ Replaced the inb() and outb() functions with direct memory
access. This allows the port to be built with the 20050414 build of
WinAVR.
*/
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
#include <stdlib.h>
#include <avr/interrupt.h>
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "serial.h"
#define serBAUD_DIV_CONSTANT ( ( unsigned portLONG ) 16 )
/* Constants for writing to UCSRB. */
#define serRX_INT_ENABLE ( ( unsigned portCHAR ) 0x80 )
#define serRX_ENABLE ( ( unsigned portCHAR ) 0x10 )
#define serTX_ENABLE ( ( unsigned portCHAR ) 0x08 )
#define serTX_INT_ENABLE ( ( unsigned portCHAR ) 0x20 )
/* Constants for writing to UCSRC. */
#define serUCSRC_SELECT ( ( unsigned portCHAR ) 0x80 )
#define serEIGHT_DATA_BITS ( ( unsigned portCHAR ) 0x06 )
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
#define vInterruptOn() \
{ \
unsigned portCHAR ucByte; \
\
ucByte = UCSRB; \
ucByte |= serTX_INT_ENABLE; \
UCSRB = ucByte; \
}
/*-----------------------------------------------------------*/
#define vInterruptOff() \
{ \
unsigned portCHAR ucInByte; \
\
ucInByte = UCSRB; \
ucInByte &= ~serTX_INT_ENABLE; \
UCSRB = ucInByte; \
}
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portLONG ulBaudRateCounter;
unsigned portCHAR ucByte;
portENTER_CRITICAL();
{
/* Create the queues used by the com test task. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
/* Calculate the baud rate register value from the equation in the
data sheet. */
ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned portLONG ) 1;
/* Set the baud rate. */
ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
UBRRL = ucByte;
ulBaudRateCounter >>= ( unsigned portLONG ) 8;
ucByte = ( unsigned portCHAR ) ( ulBaudRateCounter & ( unsigned portLONG ) 0xff );
UBRRH = ucByte;
/* Enable the Rx interrupt. The Tx interrupt will get enabled
later. Also enable the Rx and Tx. */
UCSRB = ( serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );
/* Set the data bits to 8. */
UCSRC = ( serUCSRC_SELECT | serEIGHT_DATA_BITS );
}
portEXIT_CRITICAL();
/* Unlike other ports, this serial code does not allow for more than one
com port. We therefore don't return a pointer to a port structure and can
instead just return NULL. */
return NULL;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
/* Only one port is supported. */
( void ) pxPort;
/* Get the next character from the buffer. Return false if no characters
are available, or arrive before xBlockTime expires. */
if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
{
return pdTRUE;
}
else
{
return pdFALSE;
}
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
/* Only one port is supported. */
( void ) pxPort;
/* Return false if after the block time there is no room on the Tx queue. */
if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
{
return pdFAIL;
}
vInterruptOn();
return pdPASS;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
unsigned portCHAR ucByte;
/* The parameter is not used. */
( void ) xPort;
/* Turn off the interrupts. We may also want to delete the queues and/or
re-install the original ISR. */
portENTER_CRITICAL();
{
vInterruptOff();
ucByte = UCSRB;
ucByte &= ~serRX_INT_ENABLE;
UCSRB = ucByte;
}
portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/
SIGNAL( SIG_UART_RECV )
{
signed portCHAR cChar;
signed portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Get the character and post it on the queue of Rxed characters.
If the post causes a task to wake force a context switch as the woken task
may have a higher priority than the task we have interrupted. */
cChar = UDR;
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
if( xHigherPriorityTaskWoken != pdFALSE )
{
taskYIELD();
}
}
/*-----------------------------------------------------------*/
SIGNAL( SIG_UART_DATA )
{
signed portCHAR cChar, cTaskWoken;
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
{
/* Send the next character queued for Tx. */
UDR = cChar;
}
else
{
/* Queue empty, nothing to send. */
vInterruptOff();
}
}
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