FreeRTOS/Demo/PIC32MEC14xx_MPLAB/src/Full_Demo/timertest.c

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*/

/* High speed timer test as described in main.c. */

/* System port includes */
#include "appcfg.h"
#include "platform.h"
#include "MEC14xx/mec14xx.h"
#include "MEC14xx/mec14xx_girqs.h"

/* Scheduler includes. */
#include "FreeRTOS.h"

/* The priority of the high speed timer interrupt. */
#define timerTEST_INT_PRIORITY  ( 7 )

/* MEC14xx Timer 3 Timer MMCR's */
#define portMMCR_TMR3_COUNT		*((volatile uint32_t *)(0xA0000C60ul))
#define portMMCR_TMR3_PRELOAD	*((volatile uint32_t *)(0xA0000C64ul))
#define portMMCR_TMR3_STATUS	*((volatile uint32_t *)(0xA0000C68ul))
#define portMMCR_TMR3_INTEN		*((volatile uint32_t *)(0xA0000C6Cul))
#define portMMCR_TMR3_CONTROL	*((volatile uint32_t *)(0xA0000C70ul))

/* MEC14xx JTVIC external interrupt controller
 * is mapped to M14K closely-coupled peripheral space.
 */
#define portGIRQ23_TMR3_TIMER_BITPOS	(3)
#define portGIRQ23_TMR3_TIMER_MASK		(1ul << (portGIRQ23_TMR3_TIMER_BITPOS))
#define portMMCR_JTVIC_GIRQ23_SRC		*((volatile uint32_t *)(0xBFFFC0F0ul))
#define portMMCR_JTVIC_GIRQ23_SETEN		*((volatile uint32_t *)(0xBFFFC0F4ul))
#define portMMCR_JTVIC_GIRQ23_PRIA		*((volatile uint32_t *)(0xBFFFC3F0ul))

/*-----------------------------------------------------------*/

/* Incremented every 20,000 interrupts, so should count in seconds. */
unsigned long ulHighFrequencyTimerInterrupts = 0;

/*-----------------------------------------------------------*/

void vSetupTimerTest( unsigned short usFrequencyHz )
{
/* Timer 3 is going to interrupt at usFrequencyHz Hz. */
const uint32_t ulPreload = ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / ( unsigned long ) usFrequencyHz ) - 1 );

	/* Timer 3 is used to generate interrupts above the kernel and max syscall 
	interrupt priorities. No system library calls are used here as they are not 
	guaranteed to be re-entrant. */
	portMMCR_TMR3_CONTROL = 1ul;
	portMMCR_TMR3_PRELOAD = ulPreload;
	portMMCR_TMR3_COUNT = ulPreload;
	portMMCR_TMR3_INTEN = 0x0001ul;
	portMMCR_TMR3_STATUS = 0x0001ul;
	/* Enable Timer 3, and set for auto restart, counting down. */
	portMMCR_TMR3_CONTROL |= 0x0008;
	portMMCR_TMR3_CONTROL |= 0x0020;

	/* Configure interrupts from the Timer 3. */
	portMMCR_JTVIC_GIRQ23_SRC = ( portGIRQ23_TMR3_TIMER_MASK );
	portMMCR_JTVIC_GIRQ23_PRIA &= ~( 0x0Ful << 12 );
	portMMCR_JTVIC_GIRQ23_PRIA |= ( ( portIPL_TO_CODE( timerTEST_INT_PRIORITY ) ) << 12 );
	portMMCR_JTVIC_GIRQ23_SETEN = ( portGIRQ23_TMR3_TIMER_MASK );

}
/*-----------------------------------------------------------*/

/* Interrupt handler for Timer 3 interrupts, no library functions are used
 here as they may not be re-entrant. */
void __attribute__((interrupt, nomips16)) girq23_b3( void )
{
	ulHighFrequencyTimerInterrupts++;

	/* The interrupt flag registered is shared with the lower priority timer
	 interrupts and the RTOS timer so disable interrupts here. This is not
	 strictly necessary since this is the highest priority interrupt. */
	__asm volatile( "di" );
	/* Clear the timer interrupt. */
	portMMCR_JTVIC_GIRQ23_SRC = portGIRQ23_TMR3_TIMER_MASK;
	__asm volatile( "ei" );
}