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/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org 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
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
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.
*/
/*
Changes from V3.0.0
+ ISRcode removed. Is now pulled inline to reduce stack-usage.
Changes from V3.0.1
*/
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
/* Scheduler header files. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "serial.h"
/* Hardware pin definitions. */
#define serTX_PIN bTRC6
#define serRX_PIN bTRC7
/* Bit/register definitions. */
#define serINPUT ( 1 )
#define serOUTPUT ( 0 )
#define serINTERRUPT_ENABLED ( 1 )
/* All ISR's use the PIC18 low priority interrupt. */
#define serLOW_PRIORITY ( 0 )
/*-----------------------------------------------------------*/
/* Queues to interface between comms API and interrupt routines. */
xQueueHandle xRxedChars;
xQueueHandle xCharsForTx;
portBASE_TYPE xHigherPriorityTaskWoken;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portCHAR ucQueueLength )
{
unsigned portSHORT usSPBRG;
/* Create the queues used by the ISR's to interface to tasks. */
xRxedChars = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
xCharsForTx = xQueueCreate( ucQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
portENTER_CRITICAL();
/* Setup the IO pins to enable the USART IO. */
serTX_PIN = serINPUT; // YES really! See datasheet
serRX_PIN = serINPUT;
/* Set the TX config register. */
TXSTA = 0b00100000;
// ||||||||--bit0: TX9D = n/a
// |||||||---bit1: TRMT = ReadOnly
// ||||||----bit2: BRGH = High speed
// |||||-----bit3: SENDB = n/a
// ||||------bit4: SYNC = Asynchronous mode
// |||-------bit5: TXEN = Transmit enable
// ||--------bit6: TX9 = 8-bit transmission
// |---------bit7: CSRC = n/a
/* Set the Receive config register. */
RCSTA = 0b10010000;
// ||||||||--bit0: RX9D = ReadOnly
// |||||||---bit1: OERR = ReadOnly
// ||||||----bit2: FERR = ReadOnly
// |||||-----bit3: ADDEN = n/a
// ||||------bit4: CREN = Enable receiver
// |||-------bit5: SREN = n/a
// ||--------bit6: RX9 = 8-bit reception
// |---------bit7: SPEN = Serial port enabled
/* Calculate the baud rate generator value.
We use low-speed (BRGH=0), the formula is
SPBRG = ( ( FOSC / Desired Baud Rate ) / 64 ) - 1 */
usSPBRG = ( ( APROCFREQ / ulWantedBaud ) / 64 ) - 1;
if( usSPBRG > 255 )
{
SPBRG = 255;
}
else
{
SPBRG = usSPBRG;
}
/* Set the serial interrupts to use the same priority as the tick. */
bTXIP = serLOW_PRIORITY;
bRCIP = serLOW_PRIORITY;
/* Enable the Rx interrupt now, the Tx interrupt will get enabled when
we have data to send. */
bRCIE = serINTERRUPT_ENABLED;
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;
}
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portCHAR ucBufferLength )
{
/* This is not implemented in this port.
Use xSerialPortInitMinimal() instead. */
return NULL;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, 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 ( portCHAR ) pdTRUE;
}
return ( portCHAR ) pdFALSE;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, portCHAR cOutChar, portTickType xBlockTime )
{
/* Return false if after the block time there is no room on the Tx queue. */
if( xQueueSend( xCharsForTx, ( const void * ) &cOutChar, xBlockTime ) != ( portCHAR ) pdPASS )
{
return pdFAIL;
}
/* Turn interrupt on - ensure the compiler only generates a single
instruction for this. */
bTXIE = serINTERRUPT_ENABLED;
return pdPASS;
}
/*-----------------------------------------------------------*/
void vSerialClose( xComPortHandle xPort )
{
/* Not implemented for this port.
To implement, turn off the interrupts and delete the memory
allocated to the queues. */
}
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