Configure the timer in MCC and select interrupt driven.

Once you Geneate the MCC code it will have dealt with initialising the timer ready for you to use it.

In your code

#include <definitions.h>			//Include all the MCC generated files so their fucntions can be called

//IN YOUR INITIALSE CODE
	//----- SETUP TIMER 5 -----
	//Used for: Heartbeat
	//Config done in MCC:
	//	Setup Timer:
	//		Enable interrupts: Yes
	//		Prescaller: 1:1
	//		Clock source: Internal peripheral clock
	//		Time: 1mS
	//	Setup interrupts:
	//		Priority (set for all): 3	//<<<Set as required for your application
	//		Subpriority (set for all): 0	//<<<Set as required for your application

	TMR5_CallbackRegister(TMR5_MyEventHandler, (uintptr_t)NULL);		//Register our callback function to be called when the timer interrupts
	TMR5_Start();				//Start the timer

//YOUR FUNCTION TO BE CALLED ON EACH TIMER ROLL OVER
//*********************************************
//*********************************************
//********** HEARTBEAT IRQ (Timer 5) **********
//*********************************************
//*********************************************
void TMR5_MyEventHandler(uint32_t status, uintptr_t context)
{
	
	//Toggle a pin:
	if (LATAbits.LATA6)
		LATAbits.LATA6 = 0;
	else
		LATAbits.LATA6 = 1;
	
}

Other timer functions

MCC will have created a few useful functions you can call – see the file it generated in: /config/default/peripheral/tmr/