Timer overflow interrupt

Created Wed, 29 Feb 2012 23:52:44 +0000 by Mark597

Mark597

Wed, 29 Feb 2012 23:52:44 +0000

On other projects I have used a Timer overflow interrupt to preform other tasks. I can see several posts that talk about setting up Timers and writting ISR's for various tasks. It there an include file I'm missing for functions like: OpenTimer2(T2_ON | T2_PS_1_1, 256); ConfigIntTimer2(); etc....

I have download code for projects that appear to work but I can't compile them in MPIDE. The compiler returns a NOT DECLARED IN THIS SCOPE error.

It's probably something I'm missing...

Ryan K

Thu, 01 Mar 2012 01:27:27 +0000

Hello,

#include <plib.h>

That library allows you to access all of Microchip's peripheral libraries. Although I find it easier just to modify the registers directly, saves me time looking for all the api calls and #defines that Microchip has.

http://ww1.microchip.com/downloads/en/DeviceDoc/PIC32MX_Datasheet_v2_61143B.pdf

Best Regards, Ryan K

Mark597

Thu, 01 Mar 2012 12:30:20 +0000

Hello, #include <plib.h> That library allows you to access all of Microchip's peripheral libraries. Although I find it easier just to modify the registers directly, saves me time looking for all the api calls and #defines that Microchip has. http://ww1.microchip.com/downloads/en/DeviceDoc/PIC32MX_Datasheet_v2_61143B.pdf Best Regards, Ryan K

Thanks, for the PIC32MX datasheet. The register descriptions are detailed. The datasheet I have only gives a block diagram of the Timers. I didn't include plib.h so I'll give that a try.

Thanks for your reply.

sonic

Sat, 03 Mar 2012 04:47:08 +0000

I had the same problem. The plib.h include gave me problems so I modified the registers. setup code:

// Fpb = SYS_FREQ = 80Mhz (From configuration in bootloader code)
  // Timer Prescale = 256
  // PR2 = 0xF423 = 62,499
  // interrupts every 200 ms
  // 200 ms = (PR2 + 1) * TMR Prescale / Fpb = (62499 + 1) * 256 / 80000000
  T2CON =0x0;  // stop timer and clear control register
  T2CONSET = 0x0070;  //set prescaler to 256
  TMR2 = 0x0;  // clear timer register
  PR2 = 0xF423;  // load period register
  IPC2SET = 0x0000000D;  // set priority level to 3 and subpriority level to 1
  IFS0CLR = 0x00000100;  // clear timer interupt status flag
  IEC0SET = 0x00000100;  // enable timer interrupts
  T2CONSET = 0x8000;  // start timer

interrupt code:

#ifdef __cplusplus
extern "C" {
#endif

void __ISR(_TIMER_2_VECTOR,IPL3AUTO) comms_handler(void)
{
  //mT2ClearIntFlag();  // Clear interrupt flag
  IFS0CLR = 0x00000100;
  digitalWrite(Led4, HIGH);
  oneSecond++;
}
#ifdef __cplusplus
}
#endif

Hope this helps

Mark597

Fri, 09 Mar 2012 00:29:09 +0000

Thanks for the replies.

Not including the <plib.h> was most of the problem and a couple of other things.

I did get the Timer overflow working.

Mark