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/*

    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************

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    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under

    the terms of the GNU General Public License (version 2) as published by the

    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.

    ***NOTE*** The exception to the GPL is included to allow you to distribute

    a combined work that includes FreeRTOS without being obliged to provide the

    source code for proprietary components outside of the FreeRTOS kernel.

    FreeRTOS 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 and the FreeRTOS license exception along with FreeRTOS; if not it

    can be viewed here: http://www.freertos.org/a00114.html and also obtained

    by writing to Richard Barry, contact details for whom are available on the

    FreeRTOS WEB site.

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*/

/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER for port 1.

Note that this driver is written to test the RTOS port and is not intended

to represent an optimised solution.  In particular no use is made of the DMA

peripheral. */

/* Standard include files. */

#include <stdlib.h>

/* Scheduler include files. */

#include "FreeRTOS.h"

#include "queue.h"

#include "task.h"

/* Demo application include files. */

#include "serial.h"

/* The queues used to communicate between the task code and the interrupt

service routines. */

static xQueueHandle xRxedChars;

static xQueueHandle xCharsForTx;

/* Hardware specific constants. */

#define serTX_INTERRUPT                         ( ( unsigned char ) 0x80 )

#define serRX_INTERRUPT                         ( ( unsigned char ) 0x40 )

#define serTX_ENABLE                            ( ( unsigned char ) 0x20 )

#define serRX_ENABLE                            ( ( unsigned char ) 0x10 )

/* Macros to turn on and off the serial port THRE interrupt while leaving the

other register bits in their correct state.   The Rx interrupt is always

enabled. */

#define serTX_INTERRUPT_ON()            SCR1 = serTX_INTERRUPT | serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;                                                                 

#define serTX_INTERRUPT_OFF()           SCR1 =                                   serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;

/* Bit used to switch on the channel 1 serial port in the module stop

register. */

#define serMSTP6                                        ( ( unsigned short ) 0x0040 )

/* Interrupt service routines.  Note that the Rx and Tx service routines can

cause a context switch and are therefore defined with the saveall attribute in

addition to the interrupt_handler attribute.  See the FreeRTOS.org WEB site

documentation for a full explanation.*/

void vCOM_1_Rx_ISR( void ) __attribute__ ( ( saveall, interrupt_handler ) );

void vCOM_1_Tx_ISR( void ) __attribute__ ( ( saveall, interrupt_handler ) );

void vCOM_1_Error_ISR( void ) __attribute__ ( ( interrupt_handler ) );

/*-----------------------------------------------------------*/

/*

 * Initialise port 1 for interrupt driven communications.

 */

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

        /* Create the queues used to communicate between the tasks and the

        interrupt service routines. */

        xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

        xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

        /* No parity, 8 data bits and 1 stop bit is the default so does not require

        configuration - setup the remains of the hardware. */

        portENTER_CRITICAL();

        {

                /* Turn channel 1 on. */

                MSTPCR &= ~serMSTP6;

                /* Enable the channels and the Rx interrupt.  The Tx interrupt is only

                enabled when data is being transmitted. */

                SCR1 = serRX_INTERRUPT | serTX_ENABLE | serRX_ENABLE;

                /* Bit rate settings for 22.1184MHz clock only!. */

                switch( ulWantedBaud )

                {

                        case 4800       :       BRR1 = 143;

                                                        break;

                        case 9600       :       BRR1 = 71;

                                                        break;

                        case 19200      :       BRR1 = 35;

                                                        break;

                        case 38400      :       BRR1 = 17;

                                                        break;

                        case 57600      :       BRR1 = 11;

                                                        break;

                        case 115200     :       BRR1 = 5;

                                                        break;

                        default         :       BRR1 = 5;

                                                        break;

                }

        }

        portEXIT_CRITICAL();

        /* Unlike some ports, this driver 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;

}

/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, portTickType xBlockTime )

{

        /* Get the next character from the buffer queue.  Return false if no characters

        are available, or arrive before xBlockTime expires. */

        if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )

        {

                return pdTRUE;

        }

        else

        {

                return pdFALSE;

        }

}

/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )

{

signed portBASE_TYPE xReturn = pdPASS;

        /* Return false if after the block time there is no room on the Tx queue. */

        portENTER_CRITICAL();

        {

                /* Send a character to the queue of characters waiting transmission.

                The queue is serviced by the Tx ISR. */

                if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )

                {

                        /* Could not post onto the queue. */

                        xReturn = pdFAIL;

                }

                else

                {

                        /* The message was posted onto the queue so we turn on the Tx

                        interrupt to allow the Tx ISR to remove the character from the

                        queue. */

                        serTX_INTERRUPT_ON();

                }

        }

        portEXIT_CRITICAL();

        return xReturn;

}

/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )

{

        /* Not supported. */

        ( void ) xPort;

}

/*-----------------------------------------------------------*/

void vCOM_1_Rx_ISR( void )

{

        /* This can cause a context switch so this macro must be the first line

        in the function. */

        portENTER_SWITCHING_ISR();

        /* As this is a switching ISR the local variables must be declared as

        static. */

        static char cRxByte;

        static portBASE_TYPE xHigherPriorityTaskWoken;

                xHigherPriorityTaskWoken = pdFALSE;

                /* Get the character. */

                cRxByte = RDR1;

                /* Post the character onto the queue of received characters - noting

                whether or not this wakes a task. */

                xQueueSendFromISR( xRxedChars, &cRxByte, &xHigherPriorityTaskWoken );

                /* Clear the interrupt. */

                SSR1 &= ~serRX_INTERRUPT;

        /* This must be the last line in the function.  We pass cTaskWokenByPost so

        a context switch will occur if the received character woke a task that has

        a priority higher than the task we interrupted. */

        portEXIT_SWITCHING_ISR( xHigherPriorityTaskWoken );

}

/*-----------------------------------------------------------*/

void vCOM_1_Tx_ISR( void )

{

        /* This can cause a context switch so this macro must be the first line

        in the function. */

        portENTER_SWITCHING_ISR();

        /* As this is a switching ISR the local variables must be declared as

        static. */

        static char cTxByte;

        static signed portBASE_TYPE xTaskWokenByTx;

                /* This variable is static so must be explicitly reinitialised each

                time the function executes. */

                xTaskWokenByTx = pdFALSE;

                /* The interrupt was caused by the THR becoming empty.  Are there any

                more characters to transmit?  Note whether or not the Tx interrupt has

                woken a task. */

                if( xQueueReceiveFromISR( xCharsForTx, &cTxByte, &xTaskWokenByTx ) == pdTRUE )

                {

                        /* A character was retrieved from the queue so can be sent to the

                        THR now. */

                        TDR1 = cTxByte;

                        /* Clear the interrupt. */

                        SSR1 &= ~serTX_INTERRUPT;

                }

                else

                {

                        /* Queue empty, nothing to send so turn off the Tx interrupt. */

                        serTX_INTERRUPT_OFF();

                }

        /* This must be the last line in the function.  We pass cTaskWokenByTx so

        a context switch will occur if the Tx'ed character woke a task that has

        a priority higher than the task we interrupted. */

        portEXIT_SWITCHING_ISR( xTaskWokenByTx );

}

/*-----------------------------------------------------------*/

/*

 * This ISR cannot cause a context switch so requires no special

 * considerations.

 */

void vCOM_1_Error_ISR( void )

{

volatile unsigned char ucIn;

        ucIn = SSR1;

        SSR1 = 0;

}