T/C1是16位定時(shí)器/計(jì)數(shù)器，它的計(jì)數(shù)器由兩個(gè)8位寄存器TCNT1H,TCNT1L構(gòu)成,TCNT1H是高8位寄存器，TCNT1L是低8位寄存器。最大計(jì)算值為2的16次冪，十六進(jìn)制是0xFFFF=65535.

例如：定時(shí)200ms ，晶振8MHZ，分頻系數(shù)1024，計(jì)數(shù)時(shí)鐘頻率為8MHZ/1024=8000000HZ/1024=7812.5HZ，每個(gè)計(jì)數(shù)脈沖的周期時(shí)間為1/7812.5=0.128ms，計(jì)時(shí)200ms的計(jì)數(shù)器值為：65635-200ms/0.128ms=63972=0xF9E4 ，則TCNT1H付初值為0xF9，TCNT1L付初值為0xE4.

//函數(shù)功能：實(shí)現(xiàn)PA口的led亮0.1S，滅0.9S

#include
#define uchar unsigned char
/********以下是端口初始化函數(shù)********/
void port_init()
{
DDRA = 0xFF; //PA設(shè)置為輸出口
PORTA = 0xFF; //PA輸出高電平
}
/********定時(shí)器1初始化********/
void timer1_init()
{
TCNT1H = 0xCF;//計(jì)數(shù)器置初值
TCNT1L = 0x2C;
TCCR1A |= 0x00; //普通端口模式
TCCR1B |= (1<TIMSK&=(1<

}
/********以下是主函數(shù)********/
void main(void)
{
uchar count,T1_OVR;
port_init();
timer1_init();
while(1)
}

/*定時(shí)器1中斷函數(shù)*/

#pragma interrupt_handler timer1_ovf:9

void timer1_ovf(void)

{

TCNT1H=0xCF;

TCNT1L=0x2C;

COUNT++

if (count==9)

PORTA=0x00;

if (count>=10

{

count=0;

PROTA=0xFF;

}