20100923-V6.1.0-RC2/Demo/PIC32MX_MPLAB/timertest.c

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+/*
+    FreeRTOS V6.1.0 - Copyright (C) 2010 Real Time Engineers Ltd.
+
+    ***************************************************************************
+    *                                                                         *
+    * If you are:                                                             *
+    *                                                                         *
+    *    + New to FreeRTOS,                                                   *
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+    *    + Wanting to improve your FreeRTOS skills and productivity           *
+    *                                                                         *
+    * then take a look at the FreeRTOS books - available as PDF or paperback  *
+    *                                                                         *
+    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
+    *                  http://www.FreeRTOS.org/Documentation                  *
+    *                                                                         *
+    * A pdf reference manual is also available.  Both are usually delivered   *
+    * to your inbox within 20 minutes to two hours when purchased between 8am *
+    * and 8pm GMT (although please allow up to 24 hours in case of            *
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+    *                                                                         *
+    ***************************************************************************
+
+    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 exception 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 Richard Barry, contact details for whom are available on the
+    FreeRTOS WEB site.
+
+    1 tab == 4 spaces!
+
+    http://www.FreeRTOS.org - Documentation, latest information, license and
+    contact details.
+
+    http://www.SafeRTOS.com - A version that is certified for use in safety
+    critical systems.
+
+    http://www.OpenRTOS.com - Commercial support, development, porting,
+    licensing and training services.
+*/
+
+/* High speed timer test as described in main.c. */
+
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+
+/* The maximum value the 16bit timer can contain. */
+#define timerMAX_COUNT				0xffff
+
+/* The timer 2 interrupt handler. */
+void __attribute__( (interrupt(ipl0), vector(_TIMER_2_VECTOR))) vT2InterruptWrapper( void );
+
+/*-----------------------------------------------------------*/
+
+/* Incremented every 20,000 interrupts, so should count in seconds. */
+unsigned portLONG ulHighFrequencyTimerInterrupts = 0;
+
+/* The frequency at which the timer is interrupting. */
+static unsigned portLONG ulFrequencyHz;
+
+/*-----------------------------------------------------------*/
+
+void vSetupTimerTest( unsigned portSHORT usFrequencyHz )
+{
+	/* Remember the frequency so it can be used from the ISR. */
+	ulFrequencyHz = ( unsigned portLONG ) usFrequencyHz;
+
+	/* T2 is used to generate interrupts above the kernel and max syscall interrupt
+	priority. */
+	T2CON = 0;
+	TMR2 = 0;
+
+	/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
+	PR2 = ( unsigned portSHORT ) ( ( configPERIPHERAL_CLOCK_HZ / ( unsigned portLONG ) usFrequencyHz ) - 1 );
+
+	/* Setup timer 2 interrupt priority to be above the kernel priority so 
+	the timer jitter is not effected by the kernel activity. */
+	ConfigIntTimer2( T2_INT_ON | ( configMAX_SYSCALL_INTERRUPT_PRIORITY + 1 ) );
+
+	/* Clear the interrupt as a starting condition. */
+	IFS0bits.T2IF = 0;
+
+	/* Enable the interrupt. */
+	IEC0bits.T2IE = 1;
+
+	/* Start the timer. */
+	T2CONbits.TON = 1;
+}
+/*-----------------------------------------------------------*/
+
+void vT2InterruptHandler( void )
+{
+static unsigned portLONG ulCalls = 0;
+
+	++ulCalls;
+	if( ulCalls >= ulFrequencyHz )
+	{
+		/* Increment the count that will be shown on the LCD. 
+		The increment occurs once every 20,000 interrupts so
+		ulHighFrequencyTimerInterrupts should count in seconds. */
+		ulHighFrequencyTimerInterrupts++;
+		ulCalls = 0;
+	}
+
+	/* Clear the timer interrupt. */
+	IFS0bits.T2IF = 0;
+}
+
+