NU32v2: Counters and Timers - Revision history

Lynch at 11:26, 16 January 2016

2016-01-16T11:26:16Z

2011-02-08T21:56:47Z

More Information

2011-02-03T06:31:00Z

2011-02-03T06:30:26Z

2011-01-31T10:25:42Z

Time-based Interrupts

2011-01-31T10:23:15Z

Time-based Interrupts

2011-01-31T10:20:25Z

Time-based Interrupts

2011-01-30T19:55:14Z

Time-based Interrupts

2011-01-30T19:54:48Z

Time-based Interrupts

2011-01-30T13:57:21Z

Time-based Interrupts

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+'''THIS PAGE REFERS TO A PRE-RELEASE VERSION OF THE NU32 PIC32 DEVELOPMENT BOARD.  FOR INFORMATION, SAMPLE CODE, AND VIDEOS RELATED TO THE PRODUCTION VERSION (2016 AND LATER), AND TO THE CORRESPONDING BOOK "EMBEDDED COMPUTING AND MECHATRONICS WITH THE PIC32 MICROCONTROLLER," VISIT [[NU32|THE NU32 PAGE]].'''
-'''Add information on using core timer and clock(); possibility to set the clock counter and use the 32-bit overflow interrupt.'''
 The basic function of counters is quite simple:  they count the number of pulses they have received since they were last reset (or last "rolled over").  If the pulses come from a fixed frequency clock, they can be thought of as timers, hence the words counter and timer are often used interchangeably (as in this article). I prefer to call them "counters," but Microchip's documentation mostly refers to them as timers, so we'll adopt that terminology. The pulses that are being counted may come from the internal peripheral bus clock or external sources.

← Older revision		Revision as of 21:56, 8 February 2011
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	== More Information ==		== More Information ==

			There is another timer available for our use: the ''core timer'' associated with the CPU. This counter increments by one every two clock cycles (see Section 2 of the Reference Manual). The current value can be accessed using ReadCoreTimer(), which returns an unsigned int. We can also write a value to the counter using WriteCoreTimer(unsigned int). You can set the period of the timer in the COMPARE register using OpenCoreTimer(unsigned int), and create interrupts on the period overflow.

← Older revision		Revision as of 06:31, 3 February 2011
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	'''Add information on using core timer and clock()'''		'''Add information on using core timer and clock(); possibility to set the clock counter and use the 32-bit overflow interrupt.'''

	The basic function of counters is quite simple: they count the number of pulses they have received since they were last reset (or last "rolled over"). If the pulses come from a fixed frequency clock, they can be thought of as timers, hence the words counter and timer are often used interchangeably (as in this article). I prefer to call them "counters," but Microchip's documentation mostly refers to them as timers, so we'll adopt that terminology. The pulses that are being counted may come from the internal peripheral bus clock or external sources.		The basic function of counters is quite simple: they count the number of pulses they have received since they were last reset (or last "rolled over"). If the pulses come from a fixed frequency clock, they can be thought of as timers, hence the words counter and timer are often used interchangeably (as in this article). I prefer to call them "counters," but Microchip's documentation mostly refers to them as timers, so we'll adopt that terminology. The pulses that are being counted may come from the internal peripheral bus clock or external sources.

← Older revision		Revision as of 06:30, 3 February 2011
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			'''Add information on using core timer and clock()'''

	The basic function of counters is quite simple: they count the number of pulses they have received since they were last reset (or last "rolled over"). If the pulses come from a fixed frequency clock, they can be thought of as timers, hence the words counter and timer are often used interchangeably (as in this article). I prefer to call them "counters," but Microchip's documentation mostly refers to them as timers, so we'll adopt that terminology. The pulses that are being counted may come from the internal peripheral bus clock or external sources.		The basic function of counters is quite simple: they count the number of pulses they have received since they were last reset (or last "rolled over"). If the pulses come from a fixed frequency clock, they can be thought of as timers, hence the words counter and timer are often used interchangeably (as in this article). I prefer to call them "counters," but Microchip's documentation mostly refers to them as timers, so we'll adopt that terminology. The pulses that are being counted may come from the internal peripheral bus clock or external sources.

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 }
 </pre>
-where vector refers to a constant defined in '''(find this location)''', iplx is the interrupt priority level where x is the level. yHandler can be anything you want, for example we can call the timer2 handler as Timer2Handler. There is a function associated with each interrupt that is used to clear the flag, which allows the program to return to where it was before the interrupt was generated. Without clearing the flag, the program will never exit the interrupt.
+where vector refers to a constant defined in the .h file for your particular processor (p32mx795f512l.h), iplx is the interrupt priority level where x is the level (1..7, higher numbers indicating higher priority). yHandler can be anything you want, for example we can call the timer2 handler as Timer2Handler. There is a function associated with each interrupt that is used to clear the flag, which allows the program to return to where it was before the interrupt was generated. Without clearing the flag, the program will never exit the interrupt.
 This example is going to toggle 2 LEDs at a given frequency using interrupts with timer 2. We are going to use the functions OpenTimer2() and ConfigIntTimer2() to initialize the timer and interrupts. You will see in the example code that there is also a function INTEnableSystemMultiVectoredInt() which is used to set up multi-vectored interrupts.

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 void __ISR(_TIMER_2_VECTOR, ipl2) Timer2Handler(void){
-  LED_0 = !LED_0; // toggle LED_0
+  LED_0 = ~LED_0; // toggle LED_0
   count++;
   if(count == 5){
-    LED_1 = !LED_1;	// toggle LED_1
+    LED_1 = ~LED_1;	// toggle LED_1
 		count = 0;
 		}

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   // enable multi-vector interrupts
-  INTEnableSystemMultiVectoredInt();  // note:  this is legacy syntax
+  INTEnableSystemMultiVectoredInt();
   while(1) {		// infinite loop