FreeRTOS/Demo/AVR_ATMega323_IAR/serial/serial.c

/*
    FreeRTOS V8.2.0rc1 - Copyright (C) 2014 Real Time Engineers Ltd.
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.

    >>!   NOTE: The modification to the GPL is included to allow you to     !<<
    >>!   distribute a combined work that includes FreeRTOS without being   !<<
    >>!   obliged to provide the source code for proprietary components     !<<
    >>!   outside of the FreeRTOS kernel.                                   !<<

    FreeRTOS 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.  Full license text is available on the following
    link: http://www.freertos.org/a00114.html

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?".  Have you defined configASSERT()?  *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
     *                                                                       *
    ***************************************************************************

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that is more than just the market leader, it     *
     *    is the industry's de facto standard.                               *
     *                                                                       *
     *    Help yourself get started quickly while simultaneously helping     *
     *    to support the FreeRTOS project by purchasing a FreeRTOS           *
     *    tutorial book, reference manual, or both:                          *
     *    http://www.FreeRTOS.org/Documentation                              *
     *                                                                       *
    ***************************************************************************

    ***************************************************************************
     *                                                                       *
     *   Investing in training allows your team to be as productive as       *
     *   possible as early as possible, lowering your overall development    *
     *   cost, and enabling you to bring a more robust product to market     *
     *   earlier than would otherwise be possible.  Richard Barry is both    *
     *   the architect and key author of FreeRTOS, and so also the world's   *
     *   leading authority on what is the world's most popular real time     *
     *   kernel for deeply embedded MCU designs.  Obtaining your training    *
     *   from Richard ensures your team will gain directly from his in-depth *
     *   product knowledge and years of usage experience.  Contact Real Time *
     *   Engineers Ltd to enquire about the FreeRTOS Masterclass, presented  *
     *   by Richard Barry:  http://www.FreeRTOS.org/contact
     *                                                                       *
    ***************************************************************************

    ***************************************************************************
     *                                                                       *
     *    You are receiving this top quality software for free.  Please play *
     *    fair and reciprocate by reporting any suspected issues and         *
     *    participating in the community forum:                              *
     *    http://www.FreeRTOS.org/support                                    *
     *                                                                       *
     *    Thank you!                                                         *
     *                                                                       *
    ***************************************************************************

    http://www.FreeRTOS.org - Documentation, books, training, latest versions,
    license and Real Time Engineers Ltd. contact details.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, a DOS
    compatible FAT file system, and our tiny thread aware UDP/IP stack.

    http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
    Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
    Integrity Systems ltd. to sell under the OpenRTOS brand.  Low cost OpenRTOS
    licenses offer ticketed support, indemnification and commercial middleware.

    http://www.SafeRTOS.com - High Integrity Systems also provide a safety
    engineered and independently SIL3 certified version for use in safety and
    mission critical applications that require provable dependability.

    1 tab == 4 spaces!
*/


/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR IAR AVR PORT. */


#include <stdlib.h>
#include "FreeRTOS.h"
#include "queue.h"
#include "task.h"
#include "serial.h"

#define serBAUD_DIV_CONSTANT			( ( unsigned long ) 16 )

/* Constants for writing to UCSRB. */
#define serRX_INT_ENABLE				( ( unsigned char ) 0x80 )
#define serRX_ENABLE					( ( unsigned char ) 0x10 )
#define serTX_ENABLE					( ( unsigned char ) 0x08 )
#define serTX_INT_ENABLE				( ( unsigned char ) 0x20 )

/* Constants for writing to UCSRC. */
#define serUCSRC_SELECT					( ( unsigned char ) 0x80 )
#define serEIGHT_DATA_BITS				( ( unsigned char ) 0x06 )

static QueueHandle_t xRxedChars;
static QueueHandle_t xCharsForTx;

#define vInterruptOn()										\
{															\
	unsigned char ucByte;								\
															\
	ucByte = UCSRB;											\
	ucByte |= serTX_INT_ENABLE;								\
	outb( UCSRB, ucByte );									\
}																				
/*-----------------------------------------------------------*/

#define vInterruptOff()										\
{															\
	unsigned char ucByte;								\
															\
	ucByte = UCSRB;											\
	ucByte &= ~serTX_INT_ENABLE;							\
	outb( UCSRB, ucByte );									\
}
/*-----------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned long ulBaudRateCounter;
unsigned char ucByte;

	portENTER_CRITICAL();
	{
		/* Create the queues used by the com test task. */
		xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
		xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

		/* Calculate the baud rate register value from the equation in the
		data sheet. */
		ulBaudRateCounter = ( configCPU_CLOCK_HZ / ( serBAUD_DIV_CONSTANT * ulWantedBaud ) ) - ( unsigned long ) 1;

		/* Set the baud rate. */	
		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
		outb( UBRRL, ucByte );

		ulBaudRateCounter >>= ( unsigned long ) 8;
		ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 0xff );	
		outb( UBRRH, ucByte );

		/* Enable the Rx interrupt.  The Tx interrupt will get enabled
		later. Also enable the Rx and Tx. */
		outb( UCSRB, serRX_INT_ENABLE | serRX_ENABLE | serTX_ENABLE );

		/* Set the data bits to 8. */
		outb( 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 char *pcRxedChar, TickType_t xBlockTime )
{
	/* 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 char cOutChar, TickType_t xBlockTime )
{
	/* 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 char ucByte;

	/* 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;
		outb( UCSRB, ucByte );
	}
	portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/

__interrupt void SIG_UART_RECV( void )
{
signed char ucChar, 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. */
	ucChar = UDR;

	xQueueSendFromISR( xRxedChars, &ucChar, &xHigherPriorityTaskWoken );

	if( xHigherPriorityTaskWoken != pdFALSE )
	{
		taskYIELD();
	}
}
/*-----------------------------------------------------------*/

__interrupt void SIG_UART_DATA( void )
{
signed char cChar, cTaskWoken = pdFALSE;

	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
	{
		/* Send the next character queued for Tx. */
		outb( UDR, cChar );
	}
	else
	{
		/* Queue empty, nothing to send. */
		vInterruptOff();
	}
}