blob: 3441cd736e14e47fe5fce05042aa491629da09be [file] [log] [blame]
/*
FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
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 modification 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 Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
*/
/* High speed timer test as described in main.c. */
/* Scheduler includes. */
#include "FreeRTOS.h"
/* Demo includes. */
#include "partest.h"
/* The number of interrupts to pass before we start looking at the jitter. */
#define timerSETTLE_TIME 5
/* The maximum value the 16bit timer can contain. */
#define timerMAX_COUNT 0xffff
/*-----------------------------------------------------------*/
/*
* Measure the time between this interrupt and the previous interrupt to
* calculate the timing jitter. Remember the maximum value the jitter has
* ever been calculated to be.
*/
static void prvCalculateAndStoreJitter( void );
/*-----------------------------------------------------------*/
/* The maximum time (in processor clocks) between two consecutive timer
interrupts so far. */
unsigned portSHORT usMaxJitter = 0;
/*-----------------------------------------------------------*/
void vSetupTimerTest( unsigned portSHORT usFrequencyHz )
{
/* T2 is used to generate interrupts. T4 is used to provide an accurate
time measurement. */
T2CON = 0;
T4CON = 0;
TMR2 = 0;
TMR4 = 0;
/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
PR2 = ( unsigned portSHORT ) ( configCPU_CLOCK_HZ / ( unsigned portLONG ) usFrequencyHz );
/* Timer 4 is going to free run from minimum to maximum value. */
PR4 = ( unsigned portSHORT ) timerMAX_COUNT;
/* Setup timer 2 interrupt priority to be above the kernel priority so
the timer jitter is not effected by the kernel activity. */
IPC1bits.T2IP = configKERNEL_INTERRUPT_PRIORITY + 1;
/* Clear the interrupt as a starting condition. */
IFS0bits.T2IF = 0;
/* Enable the interrupt. */
IEC0bits.T2IE = 1;
/* Start both timers. */
T2CONbits.TON = 1;
T4CONbits.TON = 1;
}
/*-----------------------------------------------------------*/
static void prvCalculateAndStoreJitter( void )
{
static unsigned portSHORT usLastCount = 0, usSettleCount = 0;
unsigned portSHORT usThisCount, usDifference;
/* Capture the timer value as we enter the interrupt. */
usThisCount = TMR4;
if( usSettleCount >= timerSETTLE_TIME )
{
/* What is the difference between the timer value in this interrupt
and the value from the last interrupt. */
usDifference = usThisCount - usLastCount;
/* Store the difference in the timer values if it is larger than the
currently stored largest value. The difference over and above the
expected difference will give the 'jitter' in the processing of these
interrupts. */
if( usDifference > usMaxJitter )
{
usMaxJitter = usDifference;
}
}
else
{
/* Don't bother storing any values for the first couple of
interrupts. */
usSettleCount++;
}
/* Remember what the timer value was this time through, so we can calculate
the difference the next time through. */
usLastCount = usThisCount;
}
/*-----------------------------------------------------------*/
void __attribute__((__interrupt__, auto_psv)) _T2Interrupt( void )
{
/* Work out the time between this and the previous interrupt. */
prvCalculateAndStoreJitter();
/* Clear the timer interrupt. */
IFS0bits.T2IF = 0;
}