strongchen

你在中断服务程序里没有清中断标志，实际上你的延时完全是靠“if(counter%25000==0)”完成的，当然无法通过MCPR1和MCPR0改变。把程序照如下修改试试：

long int counter,temp1;
byte flag;
byte value_lamp,cycle2;


#pragma CODE_SEG __NEAR_SEG NON_BANKED
interrupt 26 void Timer_ISR(void){

counter++;
/*
if(counter%25000==0) { //dalay 1s
flag = 1;
counter = 0;
temp1 = MCCNT;
//MCCTL_MCZI = 0; // MDC ÆÁ±ÎÖжÏ
//MCCNT = 0xC350;
// PORTB = 0xe7;
}
*/

/* clear RTIF bit */
//TFLG2_TOF = 1;

flag = 1;
MCFLG_MCZF = 1;
}
#pragma CODE_SEG DEFAULT


void main(void) {
/* put your own code here */

temp1 =0;
counter = 0;
flag = 0;
value_lamp = 0xaa;


DDRB=0xff; /* PTB as output */
PORTB=0x7e; /* LEDs off */

//MCCTL_MCEN = 1; // MDCÔÊÐí¹¤×÷
MCCTL_MODMC = 1; // MDCÁ¬Ðø¹¤×÷·½Ê½ ,
MCCTL_MCPR0 = 0;
MCCTL_MCPR1 = 0; // [MCPR1 MCPR0] set Prescaler Rate -->
// [00]:1 [01]:4 [10]:8 [11]:16
MCCTL_MCZI = 1; // MDC ÔÊÐíÖжÏ
MCCTL_MCEN = 1; // MDCÔÊÐí¹¤×÷

//MCCNT = 0xc350;//¼ÆÊý50000 //²»Æð×÷ÓÃ1

EnableInterrupts;
for(;;) {

//MCCTL_MCZI = 1; // MDC ÔÊÐíÖжÏ
if(flag==1){
value_lamp = ~value_lamp ;
PORTB = value_lamp;
flag = 0;
}
} /* wait forever */
/* please make sure that you never leave this function */
}