blob: 773653a00190f40850a5d2cf989ac9f8bdd83722 [file] [log] [blame]
FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
* *
* 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 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
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: 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?" *
* *
* *
* *
*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand. - 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. */
#include <device.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
/* The set frequency of the interrupt. Deviations from this are measured as
the jitter. */
#define timerINTERRUPT_FREQUENCY ( ( unsigned portSHORT ) 20000 )
/* The expected time between each of the timer interrupts - if the jitter was
zero. */
/* The number of interrupts to pass before we start looking at the jitter. */
#define timerSETTLE_TIME 5
* Configures the two timers used to perform the test.
void vSetupTimerTest( void );
/* Interrupt handler in which the jitter is measured. */
/* Stores the value of the maximum recorded jitter between interrupts. */
volatile unsigned portSHORT usMaxJitter = 0;
void vSetupTimerTest( void )
/* Install the ISR. */
static unsigned short usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
unsigned short usThisCount, usDifference;
/* Capture the free running timer value as we enter the interrupt. */
usThisCount = Timer_48MHz_ReadCounter();
if( usSettleCount >= timerSETTLE_TIME )
/* What is the difference between the timer value in this interrupt
and the value from the last interrupt. Timer counts down. */
usDifference = usLastCount + ~usThisCount + 1;
/* 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 > usMaxDifference )
usMaxDifference = usDifference;
/* Calculate the Jitter based on the difference we expect. */
usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
/* Don't bother storing any values for the first couple of
interrupts. */
/* Remember what the timer value was this time through, so we can calculate
the difference the next time through. */
usLastCount = usThisCount;