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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). 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 exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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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 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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portBASE_TYPE xHigherPriorityTaskWoken;
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/*-----------------------------------------------------------*/
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xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned char ucQueueLength )
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{
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unsigned short 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( char ) );
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xCharsForTx = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );
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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 char 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, 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 ( char ) pdTRUE;
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}
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return ( char ) pdFALSE;
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, 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 ) != ( char ) 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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