PIC16F877A TIMER1计数操作

Title:PIC16F877A TIMER1计数操作
Author:hnrain
Date:2010-12-28

使用前置分频器
T1CKPS1 T1CKPS1
0 0 1 分频 TMR1时钟为晶振时钟/(4*1)
0 1 2 分频 TMR1时钟为晶振时钟/(4*2)
1 0 4 分频 TMR1时钟为晶振时钟/(4*4)
1 1 8 分频 TMR1时钟为晶振时钟/(4*8)
TMR1是16位宽度的TMR1由2个8位的可读写的寄存器TMR1H和TMR1L组成。

TMR1有专门的启停控制位TMR1ON，通过软件可以任意启动或暂停TMR1计数功能。

T1CON:TIMER1 CONTROL REGISTER

bit7-6 unimplemented :Read as ‘0’

bit5-4 T1CKPS1:T1CKPS0:Timer1 input Clock Prescale Select bits

11=1:8 prescale value

10=1:4 prescale value

01=1:2 prescale value

00=1:1 prescale value

bit3 T1OSCEN:Timer1 Oscillator Enable Control bit

1 = Oscillator is enable

0 = Oscillator is shut-off

bit2 T1SYNC:Timer1 External Clock Input Synchronization Control bit

when TMR1CS = 1

1= Do not synchronize external clock input

0= Synchronize external clock input

when TMR1CS = 0

This bit is ignored .Timer1 uses the internal clock when TMR1CS = 0.

bit1 TMR1CS:Timer1 Clock Source Select bit

1 = External clock from pin RC0/T1OSO/T1CKI

0 = Internal clock

bit0 TMR1ON:Timer1 on bit

1 = enables timer1

0 = stops timer1
说明：作用在TMR1的计数状态，计数信号从RC0/T1CKI输入，
当来一个上升沿时，采集到一个有效的信号，计数到TMR1L,TMR1H中。
当计满时就会产生中断信号。
***********************/
#include
#include "../head/config.h"

__CONFIG(HS&WDTDIS&LVPDIS&PWRTEN);

void main(void)
{
T1CKPS0 = 0;
T1CKPS1 = 0;//不分频

TMR1L = (65536 - 1)%256;//TMR1L,TMR1H赋初值
TMR1H = (65536 - 1)/256;
T1SYNC = 1;//TMR1异步计数器
TMR1CS = 1;
GIE = 1;//打开全局中断
PEIE = 1;//打开外部中断
TMR1IE = 1;//TMR1中断打开
TMR1ON = 1;
PORTD = 0x00;
TRISD = 0x00;
while(1){}
}

void interrupt ISR(void)
{
TMR1L = (65536 - 1)%256;//重新赋值
TMR1H = (65536 - 1)/256;
if(TMR1IE && TMR1IF)
{
TMR1IF = 0;
PORTD = ~PORTD;
}
}