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147 lines
4.5 KiB
C
147 lines
4.5 KiB
C
/*
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* FreeRTOS Kernel V10.2.1
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* Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* http://www.FreeRTOS.org
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* http://aws.amazon.com/freertos
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*
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* 1 tab == 4 spaces!
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*/
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/*
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* High frequency timer test as described in main.c.
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*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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/* Hardware specifics. */
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#include "iodefine.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 ( ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / 8UL ) / timerINTERRUPT_FREQUENCY ) )
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/* The highest available interrupt priority. */
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#define timerHIGHEST_PRIORITY ( 15 )
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/* Misc defines. */
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#define timerTIMER_3_COUNT_VALUE ( *( ( unsigned short * ) 0x8801a ) ) /*( CMT3.CMCNT )*/
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/*-----------------------------------------------------------*/
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/* Interrupt handler in which the jitter is measured. */
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void vTimer2_ISR_Handler( void ) __attribute__((interrupt));
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/* Stores the value of the maximum recorded jitter between interrupts. This is
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displayed on one of the served web pages. */
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volatile unsigned short usMaxJitter = 0;
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/* Counts the number of high frequency interrupts - used to generate the run
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time stats. */
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volatile unsigned long ulHighFrequencyTickCount = 0UL;
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/*-----------------------------------------------------------*/
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void vSetupHighFrequencyTimer( void )
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{
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/* Timer CMT2 is used to generate the interrupts, and CMT3 is used
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to measure the jitter. */
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/* Enable compare match timer 2 and 3. */
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MSTP( CMT2 ) = 0;
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MSTP( CMT3 ) = 0;
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/* Interrupt on compare match. */
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CMT2.CMCR.BIT.CMIE = 1;
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/* Set the compare match value. */
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CMT2.CMCOR = ( unsigned short ) ( ( ( configPERIPHERAL_CLOCK_HZ / timerINTERRUPT_FREQUENCY ) -1 ) / 8 );
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/* Divide the PCLK by 8. */
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CMT2.CMCR.BIT.CKS = 0;
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CMT3.CMCR.BIT.CKS = 0;
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/* Enable the interrupt... */
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_IEN( _CMT2_CMI2 ) = 1;
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/* ...and set its priority to the maximum possible, this is above the priority
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set by configMAX_SYSCALL_INTERRUPT_PRIORITY so will nest. */
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_IPR( _CMT2_CMI2 ) = timerHIGHEST_PRIORITY;
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/* Start the timers. */
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CMT.CMSTR1.BIT.STR2 = 1;
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CMT.CMSTR1.BIT.STR3 = 1;
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}
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/*-----------------------------------------------------------*/
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void vTimer2_ISR_Handler( void )
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{
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volatile unsigned short usCurrentCount;
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static unsigned short usMaxCount = 0;
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static unsigned long ulErrorCount = 0UL;
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/* This is the highest priority interrupt in the system, so there is no
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advantage to re-enabling interrupts here.
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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. First stop the clock. */
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CMT.CMSTR1.BIT.STR3 = 0;
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portNOP();
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portNOP();
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usCurrentCount = timerTIMER_3_COUNT_VALUE;
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/* Is this the largest count we have measured yet? */
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if( usCurrentCount > usMaxCount )
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{
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if( usCurrentCount > timerEXPECTED_DIFFERENCE_VALUE )
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{
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usMaxJitter = usCurrentCount - timerEXPECTED_DIFFERENCE_VALUE;
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}
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else
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{
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/* This should not happen! */
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ulErrorCount++;
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}
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usMaxCount = usCurrentCount;
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}
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/* Used to generate the run time stats. */
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ulHighFrequencyTickCount++;
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/* Clear the timer. */
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timerTIMER_3_COUNT_VALUE = 0;
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/* Then start the clock again. */
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CMT.CMSTR1.BIT.STR3 = 1;
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}
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