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20120401V7.1.1-RC1/Demo/PIC18_MPLAB/serial/serial.c
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20120401V7.1.1-RC1/Demo/PIC18_MPLAB/serial/serial.c
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/*
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FreeRTOS V7.1.0 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* FreeRTOS tutorial books are available in pdf and paperback. *
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* Complete, revised, and edited pdf reference manuals are also *
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* available. *
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* *
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* Purchasing FreeRTOS documentation will not only help you, by *
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* ensuring you get running as quickly as possible and with an *
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* in-depth knowledge of how to use FreeRTOS, it will also help *
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* the FreeRTOS project to continue with its mission of providing *
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* professional grade, cross platform, de facto standard solutions *
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* for microcontrollers - completely free of charge! *
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* *
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* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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* *
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* Thank you for using FreeRTOS, and thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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>>>NOTE<<< The modification to the GPL is included to allow you to
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distribute a combined work that includes FreeRTOS without being obliged to
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provide the source code for proprietary components outside of the FreeRTOS
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kernel. FreeRTOS is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*
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Changes from V1.2.5
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+ Clear overrun errors in the Rx ISR. Overrun errors prevent any further
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characters being received.
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Changes from V2.0.0
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+ Use portTickType in place of unsigned pdLONG for delay periods.
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+ cQueueReieveFromISR() used in place of xQueueReceive() in ISR.
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*/
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/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
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/* Scheduler header files. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "serial.h"
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#include "queue.h"
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/*
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* Prototypes for ISR's. The PIC architecture means that these functions
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* have to be called from port.c. The prototypes are not however included
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* in the header as the header is common to all ports.
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*/
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void vSerialTxISR( void );
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void vSerialRxISR( void );
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/* Hardware pin definitions. */
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#define serTX_PIN TRISCbits.TRISC6
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#define serRX_PIN TRISCbits.TRISC7
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/* Bit/register definitions. */
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#define serINPUT ( 1 )
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#define serOUTPUT ( 0 )
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#define serTX_ENABLE ( ( unsigned short ) 1 )
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#define serRX_ENABLE ( ( unsigned short ) 1 )
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#define serHIGH_SPEED ( ( unsigned short ) 1 )
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#define serCONTINUOUS_RX ( ( unsigned short ) 1 )
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#define serCLEAR_OVERRUN ( ( unsigned short ) 0 )
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#define serINTERRUPT_ENABLED ( ( unsigned short ) 1 )
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#define serINTERRUPT_DISABLED ( ( unsigned short ) 0 )
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/* All ISR's use the PIC18 low priority interrupt. */
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#define serLOW_PRIORITY ( 0 )
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/*-----------------------------------------------------------*/
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/* Queues to interface between comms API and interrupt routines. */
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static xQueueHandle xRxedChars;
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static xQueueHandle xCharsForTx;
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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{
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unsigned long ulBaud;
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/* Calculate the baud rate generator constant.
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SPBRG = ( (FOSC / Desired Baud Rate) / 16 ) - 1 */
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ulBaud = configCPU_CLOCK_HZ / ulWantedBaud;
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ulBaud /= ( unsigned long ) 16;
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ulBaud -= ( unsigned long ) 1;
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/* Create the queues used by the ISR's to interface to tasks. */
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xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
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xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
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portENTER_CRITICAL();
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{
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/* Start with config registers cleared, so we can just set the wanted
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bits. */
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TXSTA = ( unsigned short ) 0;
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RCSTA = ( unsigned short ) 0;
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/* Set the baud rate generator using the above calculated constant. */
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SPBRG = ( unsigned char ) ulBaud;
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/* Setup the IO pins to enable the USART IO. */
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serTX_PIN = serOUTPUT;
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serRX_PIN = serINPUT;
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/* Set the serial interrupts to use the same priority as the tick. */
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IPR1bits.TXIP = serLOW_PRIORITY;
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IPR1bits.RCIP = serLOW_PRIORITY;
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/* Setup Tx configuration. */
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TXSTAbits.BRGH = serHIGH_SPEED;
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TXSTAbits.TXEN = serTX_ENABLE;
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/* Setup Rx configuration. */
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RCSTAbits.SPEN = serRX_ENABLE;
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RCSTAbits.CREN = serCONTINUOUS_RX;
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/* Enable the Rx interrupt now, the Tx interrupt will get enabled when
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we have data to send. */
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PIE1bits.RCIE = serINTERRUPT_ENABLED;
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}
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portEXIT_CRITICAL();
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/* Unlike other ports, this serial code does not allow for more than one
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com port. We therefore don't return a pointer to a port structure and
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can instead just return NULL. */
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return NULL;
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}
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portBASE_TYPE uxBufferLength )
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{
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/* This is not implemented in this port.
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Use xSerialPortInitMinimal() instead. */
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )
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{
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/* Get the next character from the buffer. Return false if no characters
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are available, or arrive before xBlockTime expires. */
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if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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{
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return pdTRUE;
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}
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else
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{
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return pdFALSE;
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}
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
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{
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/* Return false if after the block time there is no room on the Tx queue. */
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if( xQueueSend( xCharsForTx, ( const void * ) &cOutChar, xBlockTime ) != pdPASS )
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{
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return pdFAIL;
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}
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/* Turn interrupt on - ensure the compiler only generates a single
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instruction for this. */
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PIE1bits.TXIE = serINTERRUPT_ENABLED;
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return pdPASS;
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}
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/*-----------------------------------------------------------*/
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void vSerialClose( xComPortHandle xPort )
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{
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/* Not implemented for this port.
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To implement, turn off the interrupts and delete the memory
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allocated to the queues. */
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}
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/*-----------------------------------------------------------*/
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#pragma interruptlow vSerialRxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")
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void vSerialRxISR( void )
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{
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char cChar;
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portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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/* Get the character and post it on the queue of Rxed characters.
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If the post causes a task to wake force a context switch as the woken task
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may have a higher priority than the task we have interrupted. */
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cChar = RCREG;
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/* Clear any overrun errors. */
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if( RCSTAbits.OERR )
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{
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RCSTAbits.CREN = serCLEAR_OVERRUN;
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RCSTAbits.CREN = serCONTINUOUS_RX;
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}
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xQueueSendFromISR( xRxedChars, ( const void * ) &cChar, &xHigherPriorityTaskWoken );
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if( xHigherPriorityTaskWoken )
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{
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taskYIELD();
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}
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}
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/*-----------------------------------------------------------*/
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#pragma interruptlow vSerialTxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")
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void vSerialTxISR( void )
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{
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char cChar, cTaskWoken = pdFALSE;
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if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
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{
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/* Send the next character queued for Tx. */
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TXREG = cChar;
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}
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else
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{
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/* Queue empty, nothing to send. */
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PIE1bits.TXIE = serINTERRUPT_DISABLED;
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}
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}
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