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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 V1.2.5
+ Clear overrun errors in the Rx ISR. Overrun errors prevent any further
characters being received.
Changes from V2.0.0
+ Use portTickType in place of unsigned pdLONG for delay periods.
+ cQueueReieveFromISR() used in place of xQueueReceive() in ISR.
*/
/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */
/* Scheduler header files. */
#include "FreeRTOS.h"
#include "task.h"
#include "serial.h"
#include "queue.h"
/*
* Prototypes for ISR's. The PIC architecture means that these functions
* have to be called from port.c. The prototypes are not however included
* in the header as the header is common to all ports.
*/
void vSerialTxISR( void );
void vSerialRxISR( void );
/* Hardware pin definitions. */
#define serTX_PIN TRISCbits.TRISC6
#define serRX_PIN TRISCbits.TRISC7
/* Bit/register definitions. */
#define serINPUT ( 1 )
#define serOUTPUT ( 0 )
#define serTX_ENABLE ( ( unsigned portSHORT ) 1 )
#define serRX_ENABLE ( ( unsigned portSHORT ) 1 )
#define serHIGH_SPEED ( ( unsigned portSHORT ) 1 )
#define serCONTINUOUS_RX ( ( unsigned portSHORT ) 1 )
#define serCLEAR_OVERRUN ( ( unsigned portSHORT ) 0 )
#define serINTERRUPT_ENABLED ( ( unsigned portSHORT ) 1 )
#define serINTERRUPT_DISABLED ( ( unsigned portSHORT ) 0 )
/* All ISR's use the PIC18 low priority interrupt. */
#define serLOW_PRIORITY ( 0 )
/*-----------------------------------------------------------*/
/* Queues to interface between comms API and interrupt routines. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;
/*-----------------------------------------------------------*/
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned portLONG ulBaud;
/* Calculate the baud rate generator constant.
SPBRG = ( (FOSC / Desired Baud Rate) / 16 ) - 1 */
ulBaud = configCPU_CLOCK_HZ / ulWantedBaud;
ulBaud /= ( unsigned portLONG ) 16;
ulBaud -= ( unsigned portLONG ) 1;
/* Create the queues used by the ISR's to interface to tasks. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( portCHAR ) );
portENTER_CRITICAL();
{
/* Start with config registers cleared, so we can just set the wanted
bits. */
TXSTA = ( unsigned portSHORT ) 0;
RCSTA = ( unsigned portSHORT ) 0;
/* Set the baud rate generator using the above calculated constant. */
SPBRG = ( unsigned portCHAR ) ulBaud;
/* Setup the IO pins to enable the USART IO. */
serTX_PIN = serOUTPUT;
serRX_PIN = serINPUT;
/* Set the serial interrupts to use the same priority as the tick. */
IPR1bits.TXIP = serLOW_PRIORITY;
IPR1bits.RCIP = serLOW_PRIORITY;
/* Setup Tx configuration. */
TXSTAbits.BRGH = serHIGH_SPEED;
TXSTAbits.TXEN = serTX_ENABLE;
/* Setup Rx configuration. */
RCSTAbits.SPEN = serRX_ENABLE;
RCSTAbits.CREN = serCONTINUOUS_RX;
/* Enable the Rx interrupt now, the Tx interrupt will get enabled when
we have data to send. */
PIE1bits.RCIE = 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 portBASE_TYPE uxBufferLength )
{
/* This is not implemented in this port.
Use xSerialPortInitMinimal() instead. */
}
/*-----------------------------------------------------------*/
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;
}
}
/*-----------------------------------------------------------*/
portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed 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 ) != pdPASS )
{
return pdFAIL;
}
/* Turn interrupt on - ensure the compiler only generates a single
instruction for this. */
PIE1bits.TXIE = 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. */
}
/*-----------------------------------------------------------*/
#pragma interruptlow vSerialRxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")
void vSerialRxISR( void )
{
portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
/* Get the character and post it on the queue of Rxed characters.
If the post causes a task to wake force a context switch as the woken task
may have a higher priority than the task we have interrupted. */
cChar = RCREG;
/* Clear any overrun errors. */
if( RCSTAbits.OERR )
{
RCSTAbits.CREN = serCLEAR_OVERRUN;
RCSTAbits.CREN = serCONTINUOUS_RX;
}
xQueueSendFromISR( xRxedChars, ( const void * ) &cChar, &xHigherPriorityTaskWoken );
if( xHigherPriorityTaskWoken )
{
taskYIELD();
}
}
/*-----------------------------------------------------------*/
#pragma interruptlow vSerialTxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")
void vSerialTxISR( void )
{
portCHAR cChar, cTaskWoken = pdFALSE;
if( xQueueReceiveFromISR( xCharsForTx, &cChar, &cTaskWoken ) == pdTRUE )
{
/* Send the next character queued for Tx. */
TXREG = cChar;
}
else
{
/* Queue empty, nothing to send. */
PIE1bits.TXIE = serINTERRUPT_DISABLED;
}
}
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