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159 lines
6.1 KiB
C
159 lines
6.1 KiB
C
/*
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FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* FreeRTOS tutorial books are available in pdf and paperback. *
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* Complete, revised, and edited pdf reference manuals are also *
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* available. *
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* *
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* Purchasing FreeRTOS documentation will not only help you, by *
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* ensuring you get running as quickly as possible and with an *
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* in-depth knowledge of how to use FreeRTOS, it will also help *
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* the FreeRTOS project to continue with its mission of providing *
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* professional grade, cross platform, de facto standard solutions *
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* for microcontrollers - completely free of charge! *
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* *
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* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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* *
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* Thank you for using FreeRTOS, and thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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>>>NOTE<<< The modification to the GPL is included to allow you to
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distribute a combined work that includes FreeRTOS without being obliged to
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provide the source code for proprietary components outside of the FreeRTOS
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kernel. FreeRTOS is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/* High speed timer test as described in main.c. */
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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/* Library includes. */
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#include "hw_ints.h"
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#include "hw_memmap.h"
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#include "hw_types.h"
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#include "interrupt.h"
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#include "sysctl.h"
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#include "lmi_timer.h"
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#include "hw_timer.h"
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/* The set frequency of the interrupt. Deviations from this are measured as
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the jitter. */
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#define timerINTERRUPT_FREQUENCY ( 20000UL )
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/* The expected time between each of the timer interrupts - if the jitter was
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zero. */
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#define timerEXPECTED_DIFFERENCE_VALUE ( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )
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/* The highest available interrupt priority. */
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#define timerHIGHEST_PRIORITY ( 0 )
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/* Misc defines. */
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#define timerMAX_32BIT_VALUE ( 0xffffffffUL )
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#define timerTIMER_1_COUNT_VALUE ( * ( ( volatile unsigned long * ) ( ( unsigned portLONG ) TIMER1_BASE + 0x48UL ) ) )
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/*-----------------------------------------------------------*/
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/* Interrupt handler in which the jitter is measured. */
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void Timer0IntHandler( void );
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/* Stores the value of the maximum recorded jitter between interrupts. */
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volatile unsigned portLONG ulMaxJitter = 0;
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/*-----------------------------------------------------------*/
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void vSetupHighFrequencyTimer( void )
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{
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unsigned long ulFrequency;
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/* Timer zero is used to generate the interrupts, and timer 1 is used
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to measure the jitter. */
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SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER0 );
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SysCtlPeripheralEnable( SYSCTL_PERIPH_TIMER1 );
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TimerConfigure( TIMER0_BASE, TIMER_CFG_32_BIT_PER );
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TimerConfigure( TIMER1_BASE, TIMER_CFG_32_BIT_PER );
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/* Set the timer interrupt to be above the kernel - highest. */
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IntPrioritySet( INT_TIMER0A, timerHIGHEST_PRIORITY );
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/* Just used to measure time. */
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TimerLoadSet(TIMER1_BASE, TIMER_A, timerMAX_32BIT_VALUE );
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/* Ensure interrupts do not start until the scheduler is running. */
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portDISABLE_INTERRUPTS();
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/* The rate at which the timer will interrupt. */
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ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;
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TimerLoadSet( TIMER0_BASE, TIMER_A, ulFrequency );
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IntEnable( INT_TIMER0A );
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TimerIntEnable( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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/* Enable both timers. */
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TimerEnable( TIMER0_BASE, TIMER_A );
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TimerEnable( TIMER1_BASE, TIMER_A );
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}
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/*-----------------------------------------------------------*/
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void Timer0IntHandler( void )
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{
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unsigned portLONG ulDifference;
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volatile unsigned portLONG ulCurrentCount;
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static unsigned portLONG ulMaxDifference = 0, ulLastCount = 0;
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/* We use the timer 1 counter value to measure the clock cycles between
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the timer 0 interrupts. */
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ulCurrentCount = timerTIMER_1_COUNT_VALUE;
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TimerIntClear( TIMER0_BASE, TIMER_TIMA_TIMEOUT );
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if( ulCurrentCount < ulLastCount )
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{
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/* How many times has timer 1 counted since the last interrupt? */
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ulDifference = ulLastCount - ulCurrentCount;
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/* Is this the largest difference we have measured yet? */
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if( ulDifference > ulMaxDifference )
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{
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ulMaxDifference = ulDifference;
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ulMaxJitter = ulMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
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}
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}
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ulLastCount = ulCurrentCount;
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}
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