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/*
FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.
VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS provides completely free yet professionally developed, *
* robust, strictly quality controlled, supported, and cross *
* platform software that has become a de facto standard. *
* *
* Help yourself get started quickly and support the FreeRTOS *
* project by purchasing a FreeRTOS tutorial book, reference *
* manual, or both from: http://www.FreeRTOS.org/Documentation *
* *
* Thank you! *
* *
***************************************************************************
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 from 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?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
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.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
licenses offer ticketed support, indemnification and 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!
*/
/*
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 long.
+ 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 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 xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
#define vInterruptOn() \
{ \
unsigned char ucByte; \
\
ucByte = UCSRB; \
ucByte |= serTX_INT_ENABLE; \
UCSRB = ucByte; \
}
/*-----------------------------------------------------------*/
#define vInterruptOff() \
{ \
unsigned char ucInByte; \
\
ucInByte = UCSRB; \
ucInByte &= ~serTX_INT_ENABLE; \
UCSRB = ucInByte; \
}
/*-----------------------------------------------------------*/
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 );
UBRRL = ucByte;
ulBaudRateCounter >>= ( unsigned long ) 8;
ucByte = ( unsigned char ) ( ulBaudRateCounter & ( unsigned long ) 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 char *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 char 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 char 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 char 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 char 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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