先上代码

volatile unsigned long g_timer0_delay_conut = 0;void main(void)
{DISI(); //Disable all unmasked interruptsNy8b072a_Gpio_Init();//Ny8b072a_Timer1_Init();//Ny8b072a_Timer2_Init();Ny8b072a_Timer3_Init();ENI(); // Enable all unmasked interrupts			while(1){//CLRWDT();	// Clear WatchDog/*LED1 = ~LED1;LED2 = ~LED2;LED3 = ~LED3;LED4 = ~LED4;*/App_Delay_Ms(1000);}
}//10bit count down , max 0x3FF
void Ny8b072a_Timer1_Init(void)
{//1MSTMRH = 0x30; // TIMER1 higt 2bit in TMRH bit4~5 msb TMR1 = 0xE8; // Load 0xFF to TMR1 (Initial Timer1 register) low 8bitT1CR1 = C_TMR1_Reload | C_TMR1_En;	// Enable Timer1, Initial value reloaded from TMR1, Non-stop mode T1CR2 = C_TMR1_ClkSrc_Inst | C_PS1_Div2;	// Enable Prescaler1, Prescaler1 dividing rate = 1:2// Timer1 clock source is instruction clockINTE |= C_INT_TMR1;	// Enable Timer1 overflow interrupt
}//10bit count down , max 0x3FF
void Ny8b072a_Timer2_Init(void)
{//500usTMRH = 0x40;		//TIMER2 higt 2bit in TMRH bit6~7 msb TMR2 = 0xF4;	// Load 0xFF to TMR2 (Initial Timer2 register) low 8bitT2CR1 = C_TMR2_Reload | C_TMR2_En;	// Enable Timer2, Initial value reloaded from TMR2, Non-stop mode T2CR2 = C_TMR2_ClkSrc_Inst | C_PS2_Div2;	// Enable Prescaler2, Prescaler2 dividing rate = 1:2// Timer2 clock source is instruction clockINTE |= C_INT_TMR2;	// Enable Timer2 overflow interrupt
}//10bit count down , max 0x3FF
void Ny8b072a_Timer3_Init(void)
{//50usTM3RH = 0;	//TIMER3 higt 2bit in TM3RH bit4~5 msb TMR3 = 50;	// Load 0xFF to TMR3 (Initial Timer3 register) low 8bitT3CR1 = C_TMR3_Reload | C_TMR3_En;	// Enable Timer3, Initial value reloaded from TMR3, Non-stop mode T3CR2 = C_TMR3_ClkSrc_Inst | C_PS3_Div2;	// Enable Prescaler3, Prescaler3 dividing rate = 1:2// Timer3 clock source is instruction clock//这里用 |= 会报错:如果其他中断讯号刚好在此时产生的话，使用 'BSR' 指令清除中断旗标有机会误清其他的中断旗标。 (201)INTE2 = C_INE_TMR3;	// Enable Timer3 overflow interrupt
}//! interrupt service routine
void isr(void) __interrupt(0)
{		if(INTFbits.T1IF){g_timer0_delay_conut ++;if(500 == g_timer0_delay_conut ) //1MS * 500 = 500ms{LED1 ^= 1;g_timer0_delay_conut= 0;}INTF= (unsigned char)~(C_INT_TMR1);	// Clear T1IF flag bit	}if(INTFbits.T2IF){ g_timer0_delay_conut ++;if(1000 == g_timer0_delay_conut ) //500us * 1000 = 500ms{LED1 ^= 1;g_timer0_delay_conut  = 0;}INTF= (unsigned char)~(C_INT_TMR2);	// Clear T2IF flag bit	}if(INTE2bits.T3IF){ g_timer0_delay_conut ++;if(10000 == g_timer0_delay_conut )//50us * 10000 = 500ms{LED1 ^= 1;g_timer0_delay_conut = 0;}INTE2= (unsigned char)~(C_INF_TMR3);	// Clear T3IF flag bit	}
}

时钟频率	指令周期	定时器分频	TMRH	TMR1	中断计数	IO翻转周期
8M	4T	C_PS1_Div2	0	50	10 000	500ms
8M	4T	C_PS1_Div4	0	50	10 000	1000ms

表中第一行，定时器1的时间计算如下：
8 000 000 / 4 / 2 = 1 000 000，1 / 1 000 000 = 1us；
定时器1的初值计数50需要50us，这就是定时器1每次进中断的时间；
中断里10000 == g_time0_delay_conut需要的时间为 50 * 10 000 = 500 000us = 500ms。

表中第二行，定时器1的分频为4，验证时间为2分频的一倍，说明时间计算正确。

个人不建议把定时器初值设置过低(1us)，太频繁的中断容易引起意想不到的BUG，根据自己实际使用需求来设置一个合理的值。