FreeRTOS/Demo/CORTEX_STM32F103_IAR/timertest.c

/*
	FreeRTOS.org V4.7.0 - Copyright (C) 2003-2007 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

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

	A special exception to the GPL can be applied should you wish to distribute
	a combined work that includes FreeRTOS.org, without being obliged to provide
	the source code for any proprietary components.  See the licensing section
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	***************************************************************************
	See http://www.FreeRTOS.org for documentation, latest information, license
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	port sections of the online documentation.

	Also see http://www.SafeRTOS.com a version that has been certified for use
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*/

/* High speed timer test as described in main.c. */

/* Scheduler includes. */
#include "FreeRTOS.h"

/* Library includes. */
#include "stm32f10x_lib.h"
#include "stm32f10x_tim.h"
#include "stm32f10x_map.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. */
#define timerEXPECTED_DIFFERENCE_VALUE	( configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY )

/* The highest available interrupt priority. */
#define timerHIGHEST_PRIORITY			( 0 )

/* Misc defines. */
#define timerMAX_32BIT_VALUE			( 0xffffffffUL )
#define timerTIMER_1_COUNT_VALUE		( * ( ( unsigned long * ) ( TIMER1_BASE + 0x48 ) ) )

/* 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. */
void vTimer2IntHandler( void );

/* Stores the value of the maximum recorded jitter between interrupts. */
volatile unsigned portSHORT usMaxJitter = 0;

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

void vSetupTimerTest( void )
{
unsigned long ulFrequency;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;


	/* Enable timer clocks */
	RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2, ENABLE );
	RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM3, ENABLE );

	/* Initialise data. */
	TIM_DeInit( TIM2 );
	TIM_DeInit( TIM3 );
	TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );

	/* Time base configuration for timer 2 - which generates the interrupts. */
	ulFrequency = configCPU_CLOCK_HZ / timerINTERRUPT_FREQUENCY;	
	TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) ( ulFrequency & 0xffffUL );
	TIM_TimeBaseStructure.TIM_Prescaler = 0x0;
	TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure );
	TIM_ARRPreloadConfig( TIM2, ENABLE );

	
	/* Configuration for timer 3 which is used as a high resolution time
	measurement. */
	TIM_TimeBaseStructure.TIM_Period = ( unsigned portSHORT ) 0xffff;
	TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
	TIM_ARRPreloadConfig( TIM3, ENABLE );
	
	/* Enable TIM2 IT.  TIM3 does not generate an interrupt. */
	NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = timerHIGHEST_PRIORITY;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init( &NVIC_InitStructure );	
	TIM_ITConfig( TIM2, TIM_IT_Update, ENABLE );

	/* Finally, enable both timers. */
	TIM_Cmd( TIM2, ENABLE );
	TIM_Cmd( TIM3, ENABLE );
}
/*-----------------------------------------------------------*/

void vTimer2IntHandler( void )
{
static unsigned portSHORT usLastCount = 0, usSettleCount = 0, usMaxDifference = 0;
unsigned portSHORT usThisCount, usDifference;

	/* Capture the free running timer 3 value as we enter the interrupt. */
	usThisCount = TIM3->CNT;
	
	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 > usMaxDifference )
		{
			usMaxDifference = usDifference;
			usMaxJitter = usMaxDifference - timerEXPECTED_DIFFERENCE_VALUE;
		}
	}
	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;

    TIM_ClearITPendingBit( TIM2, TIM_IT_Update );
}