/* | |
FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd. | |
*************************************************************************** | |
* * | |
* If you are: * | |
* * | |
* + New to FreeRTOS, * | |
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* * | |
* "Using the FreeRTOS Real Time Kernel - a Practical Guide" * | |
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* * | |
* A pdf reference manual is also available. Both are usually delivered * | |
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*************************************************************************** | |
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 exception 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. See the GNU General Public License for | |
more details. You should have received a copy of the GNU General Public | |
License and the FreeRTOS license exception along with FreeRTOS; if not it | |
can be viewed here: http://www.freertos.org/a00114.html and also obtained | |
by writing to Richard Barry, contact details for whom are available on the | |
FreeRTOS WEB site. | |
1 tab == 4 spaces! | |
http://www.FreeRTOS.org - Documentation, latest information, license and | |
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http://www.SafeRTOS.com - A version that is certified for use in safety | |
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*/ | |
/* | |
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(); | |
} | |
} | |