peripheral_test_timer.c

很多仪器都输出同步时钟

#include "peripheral_test.h"
#include "excalibur.h"

// Prototypes

void DoEnableTimerInterrupt(void);
void DoDisableTimerInterrupt(void);

// Meat

void DoTimerMenu(void)
	{
	np_timer *timer = na_timer1;
	char c;
	long timerPeriod = 70000000;

	timer->np_timerperiodh = timerPeriod >> 16;
	timer->np_timerperiodl = timerPeriod & 0xffff;

menu:
	MenuBegin("TIMER MENU");
	MenuEntry('a',"Show Timer State");
	MenuEntry('b',"Start Timer");
	MenuEntry('c',"Stop Timer");
	MenuEntry('d',"Set Timer Continuous");
	MenuEntry('e',"Clear Timer Continuous");
	MenuEntry('f',"Enable Timer Interrupt");
	MenuEntry('g',"Disable Timer Interrupt");
	c = MenuEnd('a','g');
menuSwitch:
	switch(c)
		{
		case 'a':
			printf("<space> to show timer, <Esc> to end\n");
			while(1)
				{
				long timerVal;
				long timerPeriod;

				timer->np_timersnapl = 0;	// snapshot
				timerVal = (timer->np_timersnapl & 0x0ffff)
					+ ((long)timer->np_timersnaph << 16);
				timerPeriod = (timer->np_timerperiodl & 0x0ffff)
					+ ((long)timer->np_timerperiodh << 16);
	
				printf("Timer State Time=%8ld, Period = %8ld, Status=%d, Control=%d\n",
					timerVal,timerPeriod,
					timer->np_timerstatus,
					timer->np_timercontrol);

				while((c = rGetChar()) < 0)
					;
				if(c == 27) goto menu;
				if(c != ' ') goto menuSwitch;
				}

		case 'b':
			timer->np_timercontrol = (timer->np_timercontrol & 3)
				+ np_timercontrol_start_mask;
			break;

		case 'c':
			timer->np_timercontrol = (timer->np_timercontrol & 3)
				+ np_timercontrol_stop_mask;
			break;

		case 'd':
			timer->np_timercontrol = timer->np_timercontrol 
				| np_timercontrol_cont_mask;
			break;
	
		case 'e':
			timer->np_timercontrol = timer->np_timercontrol 
				& ~np_timercontrol_cont_mask;
			break;

		MenuCase('f',DoEnableTimerInterrupt);
		MenuCase('g',DoDisableTimerInterrupt);
		}
	
	if(c != 'q')
		goto menu;
	}

typedef struct
	{
	long interruptCount;	// increment with each interrupt
	np_timer *timer;
	} TimerISRContext;

static TimerISRContext gC = {0,0};

void MyTimerISR(int context)
	{
	TimerISRContext *c;

	c = (TimerISRContext *)context;

	c->interruptCount++;

	printf("(timer #%d!)",c->interruptCount);

	c->timer->np_timerstatus = 0;	// write anything to clear the IRQ
	}

// Turn on interrupts: enable interrupt bit, and
// install a user ISR

void DoEnableTimerInterrupt(void)
	{
	gC.timer = na_timer1;
	nr_installuserisr(na_timer1_irq,MyTimerISR,(long)&gC);

	gC.timer->np_timercontrol = gC.timer->np_timercontrol | np_timercontrol_ito_mask;

	printf("\n\nTimer interrupt enabled.\n\n");
	}

void DoDisableTimerInterrupt(void)
	{
	gC.timer = na_timer1;
	nr_installuserisr(na_timer1_irq,0,0);

	gC.timer->np_timercontrol = gC.timer->np_timercontrol & ~np_timercontrol_ito_mask;

	printf("\n\nTimer interrupt disabled.\n\n");
	}