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188 lines
6.1 KiB
C
188 lines
6.1 KiB
C
/*
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FreeRTOS.org V4.7.1 - Copyright (C) 2003-2008 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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Please ensure to read the configuration and relevant port sections of the
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online documentation.
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+++ http://www.FreeRTOS.org +++
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Documentation, latest information, license and contact details.
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+++ http://www.SafeRTOS.com +++
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A version that is certified for use in safety critical systems.
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+++ http://www.OpenRTOS.com +++
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Commercial support, development, porting, licensing and training services.
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***************************************************************************
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*/
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/*
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Changes from V3.0.0
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+ ISRcode removed. Is now pulled inline to reduce stack-usage.
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Changes from V3.0.1
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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 "queue.h"
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#include "serial.h"
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/* Hardware pin definitions. */
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#define serTX_PIN bTRC6
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#define serRX_PIN bTRC7
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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 serINTERRUPT_ENABLED ( 1 )
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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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xQueueHandle xRxedChars;
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xQueueHandle xCharsForTx;
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portCHAR ucQueueLength )
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{
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unsigned portSHORT usSPBRG;
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/* Create the queues used by the ISR's to interface to tasks. */
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xRxedChars = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
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xCharsForTx = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
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portENTER_CRITICAL();
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/* Setup the IO pins to enable the USART IO. */
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serTX_PIN = serINPUT; // YES really! See datasheet
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serRX_PIN = serINPUT;
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/* Set the TX config register. */
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TXSTA = 0b00100000;
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// ||||||||--bit0: TX9D = n/a
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// |||||||---bit1: TRMT = ReadOnly
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// ||||||----bit2: BRGH = High speed
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// |||||-----bit3: SENDB = n/a
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// ||||------bit4: SYNC = Asynchronous mode
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// |||-------bit5: TXEN = Transmit enable
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// ||--------bit6: TX9 = 8-bit transmission
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// |---------bit7: CSRC = n/a
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/* Set the Receive config register. */
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RCSTA = 0b10010000;
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// ||||||||--bit0: RX9D = ReadOnly
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// |||||||---bit1: OERR = ReadOnly
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// ||||||----bit2: FERR = ReadOnly
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// |||||-----bit3: ADDEN = n/a
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// ||||------bit4: CREN = Enable receiver
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// |||-------bit5: SREN = n/a
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// ||--------bit6: RX9 = 8-bit reception
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// |---------bit7: SPEN = Serial port enabled
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/* Calculate the baud rate generator value.
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We use low-speed (BRGH=0), the formula is
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SPBRG = ( ( FOSC / Desired Baud Rate ) / 64 ) - 1 */
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usSPBRG = ( ( APROCFREQ / ulWantedBaud ) / 64 ) - 1;
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if( usSPBRG > 255 )
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{
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SPBRG = 255;
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}
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else
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{
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SPBRG = usSPBRG;
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}
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/* Set the serial interrupts to use the same priority as the tick. */
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bTXIP = serLOW_PRIORITY;
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bRCIP = serLOW_PRIORITY;
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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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bRCIE = serINTERRUPT_ENABLED;
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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 portCHAR ucBufferLength )
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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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return NULL;
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, portCHAR *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 ( portCHAR ) pdTRUE;
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}
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return ( portCHAR ) pdFALSE;
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, portCHAR 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 ) != ( portCHAR ) 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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bTXIE = 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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