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FreeRTOS V7.4.1 - Copyright (C) 2013 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.
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*************************************************************************** - Documentation, books, training, latest versions,
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* USART PORT - connect pin 2 to pin 3 on J2.
* Instead of the normal single demo application, the PIC18F demo is split
* into several smaller programs of which this is the third. This enables the
* demo's to be executed on the RAM limited 40 pin devices. The 64 and 80 pin
* devices require a more costly development platform and are not so readily
* available.
* The RTOSDemo3 project is configured for a PIC18F452 device. Main3.c starts
* 5 tasks (including the idle task).
* The first task repeatedly transmits a string of characters on the PIC USART
* port. The second task receives the characters, checking that the correct
* sequence is maintained (i.e. what is transmitted is identical to that
* received). Each transmitted and each received character causes an LED to
* flash. See demo/common/minimal/comtest. c for more information.
* The third task continuously performs a 32 bit calculation. This is a good
* test of the context switch mechanism as the 8 bit architecture requires
* the use of several file registers to perform the 32 bit operations. See
* demo/common/minimal/integer. c for more information.
* The third task is the check task. This periodically checks that the other
* tasks are still running and have not experienced any errors. If no errors
* have been reported by either the comms or integer tasks an LED is flashed
* with a frequency mainNO_ERROR_CHECK_PERIOD. If an error is discovered the
* frequency is increased to mainERROR_FLASH_RATE.
* The check task also provides a visual indication of a system reset by
* flashing the one remaining LED (mainRESET_LED) when it starts. After
* this initial flash mainRESET_LED should remain off.
* contains important information on the use of the
* PIC18F port.
Changes from V2.0.0
+ Delay periods are now specified using variables and constants of
portTickType rather than unsigned long.
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
/* Demo app include files. */
#include "partest.h"
#include "serial.h"
#include "comtest.h"
#include "integer.h"
/* Priority definitions for the LED tasks. Other tasks just use the idle
priority. */
#define mainCOMM_TEST_PRIORITY ( tskIDLE_PRIORITY + ( unsigned portBASE_TYPE ) 2 )
#define mainCHECK_TASK_PRIORITY ( tskIDLE_PRIORITY + ( unsigned portBASE_TYPE ) 3 )
/* The period between executions of the check task before and after an error
has been discovered. If an error has been discovered the check task runs
more frequently - increasing the LED flash rate. */
#define mainNO_ERROR_CHECK_PERIOD ( ( portTickType ) 1000 / portTICK_RATE_MS )
#define mainERROR_CHECK_PERIOD ( ( portTickType ) 100 / portTICK_RATE_MS )
/* The period for which mainRESET_LED remain on every reset. */
#define mainRESET_LED_PERIOD ( ( portTickType ) 500 / portTICK_RATE_MS )
/* The LED that is toggled whenever a character is transmitted.
mainCOMM_TX_RX_LED + 1 will be toggled every time a character is received. */
#define mainCOMM_TX_RX_LED ( ( unsigned portBASE_TYPE ) 2 )
/* The LED that is flashed by the check task at a rate that indicates the
error status. */
#define mainCHECK_TASK_LED ( ( unsigned portBASE_TYPE ) 1 )
/* The LED that is flashed once upon every reset. */
#define mainRESET_LED ( ( unsigned portBASE_TYPE ) 0 )
/* Constants required for the communications. */
#define mainCOMMS_QUEUE_LENGTH ( ( unsigned portBASE_TYPE ) 5 )
#define mainBAUD_RATE ( ( unsigned long ) 57600 )
* Task function which periodically checks the other tasks for errors. Flashes
* an LED at a rate that indicates whether an error has ever been detected.
static void vErrorChecks( void *pvParameters );
/* Creates the tasks, then starts the scheduler. */
void main( void )
/* Initialise the required hardware. */
/* Initialise the block memory allocator. */
/* Start the standard comtest tasks as defined in demo/common/minimal. */
vAltStartComTestTasks( mainCOMM_TEST_PRIORITY, mainBAUD_RATE, mainCOMM_TX_RX_LED );
/* Start the standard 32bit calculation task as defined in
demo/common/minimal. */
vStartIntegerMathTasks( tskIDLE_PRIORITY );
/* Start the check task defined in this file. */
xTaskCreate( vErrorChecks, ( const char * const ) "Check", configMINIMAL_STACK_SIZE, NULL, mainCHECK_TASK_PRIORITY, NULL );
/* Start the scheduler. This will never return. */
static void vErrorChecks( void *pvParameters )
portTickType xDelayTime = mainNO_ERROR_CHECK_PERIOD;
volatile unsigned long ulDummy = 3UL;
/* Toggle the LED so we can see when a reset occurs. */
vParTestSetLED( mainRESET_LED, pdTRUE );
vTaskDelay( mainRESET_LED_PERIOD );
vParTestSetLED( mainRESET_LED, pdFALSE );
/* Cycle for ever, delaying then checking all the other tasks are still
operating without error. */
for( ;; )
/* Wait until it is time to check the other tasks. */
vTaskDelay( xDelayTime );
/* Perform an integer calculation - just to ensure the registers
get used. The result is not important. */
ulDummy *= 3UL;
/* Check all the other tasks are running, and running without ever
having an error. The delay period is lowered if an error is reported,
causing the LED to flash at a higher rate. */
if( xAreIntegerMathsTaskStillRunning() == pdFALSE )
xDelayTime = mainERROR_CHECK_PERIOD;
if( xAreComTestTasksStillRunning() == pdFALSE )
xDelayTime = mainERROR_CHECK_PERIOD;
/* Flash the LED for visual feedback. The rate of the flash will
indicate the health of the system. */
vParTestToggleLED( mainCHECK_TASK_LED );