root/webserver/example/freeRTOS/Demo/Common/Full/comtest.c

/*
        FreeRTOS V5.4.1 - Copyright (C) 2009 Real Time Engineers Ltd.

        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.  
        Alternative commercial license and support terms are also available upon 
        request.  See the licensing section of http://www.FreeRTOS.org for full 
        license details.

        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 along
        with FreeRTOS; if not, write to the Free Software Foundation, Inc., 59
        Temple Place, Suite 330, Boston, MA  02111-1307  USA.


        ***************************************************************************
        *                                                                         *
        * Looking for a quick start?  Then check out the FreeRTOS eBook!          *
        * See http://www.FreeRTOS.org/Documentation for details                   *
        *                                                                         *
        ***************************************************************************

        1 tab == 4 spaces!

        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.
*/

/**
 * Creates two tasks that operate on an interrupt driven serial port.  A loopback 
 * connector should be used so that everything that is transmitted is also received.  
 * The serial port does not use any flow control.  On a standard 9way 'D' connector 
 * pins two and three should be connected together.
 *
 * The first task repeatedly sends a string to a queue, character at a time.  The 
 * serial port interrupt will empty the queue and transmit the characters.  The 
 * task blocks for a pseudo random period before resending the string.
 *
 * The second task blocks on a queue waiting for a character to be received.  
 * Characters received by the serial port interrupt routine are posted onto the 
 * queue - unblocking the task making it ready to execute.  If this is then the 
 * highest priority task ready to run it will run immediately - with a context 
 * switch occurring at the end of the interrupt service routine.  The task 
 * receiving characters is spawned with a higher priority than the task 
 * transmitting the characters.
 *
 * With the loop back connector in place, one task will transmit a string and the 
 * other will immediately receive it.  The receiving task knows the string it 
 * expects to receive so can detect an error.
 *
 * This also creates a third task.  This is used to test semaphore usage from an
 * ISR and does nothing interesting.  
 * 
 * \page ComTestC comtest.c
 * \ingroup DemoFiles
 * <HR>
 */

/*
Changes from V1.00:
        
        + The priority of the Rx task has been lowered.  Received characters are
          now processed (read from the queue) at the idle priority, allowing low
          priority tasks to run evenly at times of a high communications overhead.

Changes from V1.01:

        + The Tx task now waits a pseudo random time between transissions.
          Previously a fixed period was used but this was not such a good test as
          interrupts fired at regular intervals.

Changes From V1.2.0:

        + Use vSerialPutString() instead of single character puts.
        + Only stop the check variable incrementing after two consecutive errors. 

Changed from V1.2.5

        + Made the Rx task 2 priorities higher than the Tx task.  Previously it was
          only 1.  This is done to tie in better with the other demo application 
          tasks.

Changes from V2.0.0

        + Delay periods are now specified using variables and constants of
          portTickType rather than unsigned portLONG.
        + Slight modification to task priorities.

*/


/* Scheduler include files. */
#include <stdlib.h>
#include <string.h>
#include "FreeRTOS.h"
#include "task.h"

/* Demo program include files. */
#include "serial.h"
#include "comtest.h"
#include "print.h"

/* The Tx task will transmit the sequence of characters at a pseudo random
interval.  This is the maximum and minimum block time between sends. */
#define comTX_MAX_BLOCK_TIME            ( ( portTickType ) 0x15e )
#define comTX_MIN_BLOCK_TIME            ( ( portTickType ) 0xc8 )

#define comMAX_CONSECUTIVE_ERRORS       ( 2 )

#define comSTACK_SIZE                           ( ( unsigned portSHORT ) 256 )

#define comRX_RELATIVE_PRIORITY         ( 1 )

/* Handle to the com port used by both tasks. */
static xComPortHandle xPort;

/* The transmit function as described at the top of the file. */
static void vComTxTask( void *pvParameters );

/* The receive function as described at the top of the file. */
static void vComRxTask( void *pvParameters );

/* The semaphore test function as described at the top of the file. */
static void vSemTestTask( void * pvParameters );

/* The string that is repeatedly transmitted. */
const portCHAR * const pcMessageToExchange =    "Send this message over and over again to check communications interrupts. "
                                                                                                "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\r\n";

/* Variables that are incremented on each cycle of each task.  These are used to 
check that both tasks are still executing. */
volatile portSHORT sTxCount = 0, sRxCount = 0, sSemCount = 0;

/* The handle to the semaphore test task. */
static xTaskHandle xSemTestTaskHandle = NULL;

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

void vStartComTestTasks( unsigned portBASE_TYPE uxPriority, eCOMPort ePort, eBaud eBaudRate )
{
const unsigned portBASE_TYPE uxBufferLength = 255;

        /* Initialise the com port then spawn both tasks. */
        xPort = xSerialPortInit( ePort, eBaudRate, serNO_PARITY, serBITS_8, serSTOP_1, uxBufferLength );
        xTaskCreate( vComTxTask, "COMTx", comSTACK_SIZE, NULL, uxPriority, NULL );
        xTaskCreate( vComRxTask, "COMRx", comSTACK_SIZE, NULL, uxPriority + comRX_RELATIVE_PRIORITY, NULL );
        xTaskCreate( vSemTestTask, "ISRSem", comSTACK_SIZE, NULL, tskIDLE_PRIORITY, &xSemTestTaskHandle );
}
/*-----------------------------------------------------------*/

static void vComTxTask( void *pvParameters )
{
const portCHAR * const pcTaskStartMsg = "COM Tx task started.\r\n";
portTickType xTimeToWait;

        /* Stop warnings. */
        ( void ) pvParameters;

        /* Queue a message for printing to say the task has started. */
        vPrintDisplayMessage( &pcTaskStartMsg );

        for( ;; )
        {
                /* Send the string to the serial port. */
                vSerialPutString( xPort, pcMessageToExchange, strlen( pcMessageToExchange ) );

                /* We have posted all the characters in the string - increment the variable 
                used to check that this task is still running, then wait before re-sending 
                the string. */
                sTxCount++;

                xTimeToWait = xTaskGetTickCount();

                /* Make sure we don't wait too long... */
                xTimeToWait %= comTX_MAX_BLOCK_TIME;

                /* ...but we do want to wait. */
                if( xTimeToWait < comTX_MIN_BLOCK_TIME )
                {
                        xTimeToWait = comTX_MIN_BLOCK_TIME;
                }

                vTaskDelay( xTimeToWait );
        }
} /*lint !e715 !e818 pvParameters is required for a task function even if it is not referenced. */
/*-----------------------------------------------------------*/

static void vComRxTask( void *pvParameters )
{
const portCHAR * const pcTaskStartMsg = "COM Rx task started.\r\n";
const portCHAR * const pcTaskErrorMsg = "COM read error\r\n";
const portCHAR * const pcTaskRestartMsg = "COM resynced\r\n";
const portCHAR * const pcTaskTimeoutMsg = "COM Rx timed out\r\n";
const portTickType xBlockTime = ( portTickType ) 0xffff / portTICK_RATE_MS;
const portCHAR *pcExpectedChar;
portBASE_TYPE xGotChar;
portCHAR cRxedChar;
portSHORT sResyncRequired, sConsecutiveErrors, sLatchedError;

        /* Stop warnings. */
        ( void ) pvParameters;

        /* Queue a message for printing to say the task has started. */
        vPrintDisplayMessage( &pcTaskStartMsg );
        
        /* The first expected character is the first character in the string. */
        pcExpectedChar = pcMessageToExchange;
        sResyncRequired = pdFALSE;
        sConsecutiveErrors = 0;
        sLatchedError = pdFALSE;

        for( ;; )
        {
                /* Receive a message from the com port interrupt routine.  If a message is 
                not yet available the call will block the task. */
                xGotChar = xSerialGetChar( xPort, &cRxedChar, xBlockTime );
                if( xGotChar == pdTRUE )
                {
                        if( sResyncRequired == pdTRUE )
                        {
                                /* We got out of sequence and are waiting for the start of the next 
                                transmission of the string. */
                                if( cRxedChar == '\n' )
                                {
                                        /* This is the end of the message so we can start again - with 
                                        the first character in the string being the next thing we expect 
                                        to receive. */
                                        pcExpectedChar = pcMessageToExchange;
                                        sResyncRequired = pdFALSE;

                                        /* Queue a message for printing to say that we are going to try 
                                        again. */
                                        vPrintDisplayMessage( &pcTaskRestartMsg );

                                        /* Stop incrementing the check variable, if consecutive errors occur. */
                                        sConsecutiveErrors++;
                                        if( sConsecutiveErrors >= comMAX_CONSECUTIVE_ERRORS )
                                        {
                                                sLatchedError = pdTRUE;
                                        }
                                }
                        }
                        else
                        {
                                /* We have received a character, but is it the expected character? */
                                if( cRxedChar != *pcExpectedChar )
                                {
                                        /* This was not the expected character so post a message for 
                                        printing to say that an error has occurred.  We will then wait 
                                        to resynchronise. */
                                        vPrintDisplayMessage( &pcTaskErrorMsg );                                        
                                        sResyncRequired = pdTRUE;
                                }
                                else
                                {
                                        /* This was the expected character so next time we will expect 
                                        the next character in the string.  Wrap back to the beginning 
                                        of the string when the null terminator has been reached. */
                                        pcExpectedChar++;
                                        if( *pcExpectedChar == '\0' )
                                        {
                                                pcExpectedChar = pcMessageToExchange;

                                                /* We have got through the entire string without error. */
                                                sConsecutiveErrors = 0;
                                        }
                                }
                        }

                        /* Increment the count that is used to check that this task is still 
                        running.  This is only done if an error has never occurred. */
                        if( sLatchedError == pdFALSE )
                        {
                                sRxCount++;                     
                        }
                }
                else
                {
                        vPrintDisplayMessage( &pcTaskTimeoutMsg );
                }
        }
} /*lint !e715 !e818 pvParameters is required for a task function even if it is not referenced. */
/*-----------------------------------------------------------*/

static void vSemTestTask( void * pvParameters )
{
const portCHAR * const pcTaskStartMsg = "ISR Semaphore test started.\r\n";
portBASE_TYPE xError = pdFALSE;

        /* Stop warnings. */
        ( void ) pvParameters;

        /* Queue a message for printing to say the task has started. */
        vPrintDisplayMessage( &pcTaskStartMsg );

        for( ;; )
        {
                if( xSerialWaitForSemaphore( xPort ) )
                {
                        if( xError == pdFALSE )
                        {
                                sSemCount++;
                        }
                }
                else
                {
                        xError = pdTRUE;
                }
        }
} /*lint !e715 !e830 !e818 pvParameters not used but function prototype must be standard for task function. */
/*-----------------------------------------------------------*/

/* This is called to check that all the created tasks are still running. */
portBASE_TYPE xAreComTestTasksStillRunning( void )
{
static portSHORT sLastTxCount = 0, sLastRxCount = 0, sLastSemCount = 0;
portBASE_TYPE xReturn;

        /* Not too worried about mutual exclusion on these variables as they are 16 
        bits and we are only reading them.  We also only care to see if they have 
        changed or not. */

        if( ( sTxCount == sLastTxCount ) || ( sRxCount == sLastRxCount ) || ( sSemCount == sLastSemCount ) )
        {
                xReturn = pdFALSE;
        }
        else
        {
                xReturn = pdTRUE;
        }

        sLastTxCount = sTxCount;
        sLastRxCount = sRxCount;
        sLastSemCount = sSemCount;

        return xReturn;
}
/*-----------------------------------------------------------*/

void vComTestUnsuspendTask( void )
{
        /* The task that is suspended on the semaphore will be referenced from the
        Suspended list as it is blocking indefinitely.  This call just checks that
        the kernel correctly detects this and does not attempt to unsuspend the
        task. */
        xTaskResumeFromISR( xSemTestTaskHandle );
}