/* | |
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" * | |
* http://www.FreeRTOS.org/Documentation * | |
* * | |
* 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 | |
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. | |
*/ | |
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. | |
* | |
* This is not a proper UART driver. It only supports one port, uses loopback | |
* mode, and is used to test interrupts that use the FreeRTOS API as part of | |
* a wider test suite. Nor is it intended to show an efficient implementation | |
* of a UART interrupt service routine as queues are used to pass individual | |
* characters one at a time! | |
*/ | |
/* Standard includes. */ | |
#include <stdlib.h> | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "queue.h" | |
#include "task.h" | |
/* Demo application includes. */ | |
#include "serial.h" | |
/* Misc. constants. */ | |
#define serNO_BLOCK ( ( portTickType ) 0 ) | |
/* The queue used to hold received characters. */ | |
static xQueueHandle xRxedChars; | |
/* The queue used to hold characters waiting transmission. */ | |
static xQueueHandle xCharsForTx; | |
/*-----------------------------------------------------------*/ | |
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) | |
{ | |
unsigned portLONG ulBaudRateCount; | |
/* Initialise the hardware. */ | |
/* Generate the baud rate constants for the wanted baud rate. */ | |
ulBaudRateCount = configCPU_CLOCK_HZ / ulWantedBaud; | |
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 ) ); | |
/* Reset UART. */ | |
UCA1CTL1 |= UCSWRST; | |
/* Use SMCLK. */ | |
UCA1CTL1 = UCSSEL0 | UCSSEL1; | |
/* Setup baud rate low byte. */ | |
UCA1BR0 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff ); | |
/* Setup baud rate high byte. */ | |
ulBaudRateCount >>= 8UL; | |
UCA1BR1 = ( unsigned portCHAR ) ( ulBaudRateCount & ( unsigned portLONG ) 0xff ); | |
/* UCLISTEN sets loopback mode! */ | |
UCA1STAT = UCLISTEN; | |
/* Enable interrupts. */ | |
UCA1IE |= UCRXIE; | |
/* Take out of reset. */ | |
UCA1CTL1 &= ~UCSWRST; | |
} | |
portEXIT_CRITICAL(); | |
/* Note the comments at the top of this file about this not being a generic | |
UART driver. */ | |
return NULL; | |
} | |
/*-----------------------------------------------------------*/ | |
signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType 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 portCHAR cOutChar, portTickType xBlockTime ) | |
{ | |
signed portBASE_TYPE xReturn; | |
/* Send the next character to the queue of characters waiting transmission, | |
then enable the UART Tx interrupt, just in case UART transmission has already | |
completed and switched itself off. */ | |
xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime ); | |
UCA1IE |= UCTXIE; | |
return xReturn; | |
} | |
/*-----------------------------------------------------------*/ | |
#pragma vector=USCI_A1_VECTOR | |
static __interrupt void prvUSCI_A1_ISR( void ) | |
{ | |
signed portCHAR cChar; | |
portBASE_TYPE xTaskWoken = pdFALSE; | |
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE; | |
while( ( UCA1IFG & UCRXIFG ) != 0 ) | |
{ | |
/* Get the character from the UART and post it on the queue of Rxed | |
characters. */ | |
cChar = UCA1RXBUF; | |
xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ); | |
} | |
/* If there is a Tx interrupt pending and the tx interrupts are enabled. */ | |
if( ( UCA1IFG & UCTXIFG ) != 0 ) | |
{ | |
/* The previous character has been transmitted. See if there are any | |
further characters waiting transmission. */ | |
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xTaskWoken ) == pdTRUE ) | |
{ | |
/* There was another character queued - transmit it now. */ | |
UCA1TXBUF = cChar; | |
} | |
else | |
{ | |
/* There were no other characters to transmit - disable the Tx | |
interrupt. */ | |
UCA1IE &= ~UCTXIE; | |
} | |
} | |
__bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF ); | |
/* If writing to a queue caused a task to unblock, and the unblocked task | |
has a priority equal to or above the task that this interrupt interrupted, | |
then lHigherPriorityTaskWoken will have been set to pdTRUE internally within | |
xQueuesendFromISR(), and portEND_SWITCHING_ISR() will ensure that this | |
interrupt returns directly to the higher priority unblocked task. | |
THIS MUST BE THE LAST THING DONE IN THE ISR. */ | |
portYIELD_FROM_ISR( xHigherPriorityTaskWoken ); | |
} | |