单片机捕捉不到编码器脉冲 - 智能车制作

#include <hidef.h>
#include <MC9S12XS128.h>
#pragma LINK_INFO DERIVATIVE "mc9s12xs128"
//接口定义: 编码器脉冲中断信号接PT7
void shijian(void);
void chaopin(void); //超频程序
void TIM_init(void);//定时程序
int chesudu;
void main(void)
{
chaopin(); //超频函数初始化
shijian() ;
TIM_init();//计数器函数初始化
for(;;)
{
//把要处理的函数放在这里
}
}
void chaopin(void)//64M
{
CLKSEL=0X00;
PLLCTL_PLLON=1;
SYNR =0xc0 | 0x07;
REFDV=0xc0 | 0x01;
POSTDIV=0x00;
_asm(nop);
_asm(nop);
_asm(nop);
_asm(nop);
while(!(CRGFLG_LOCK==1));
CLKSEL_PLLSEL =1;
}
void TIM_init(void)
{
PACTL=0X50; //Pulse Accumulator Control Register 01010000，捕捉上升沿，Use timer prescaler clock as timer counter clock
PACNT=0X0000; //Pulse Accumulators Count Registers
}
void shijian(void) { //Periodic Interrupt Timer
PITCFLMT_PITE=0; //PIT is disabled
PITCE_PCE0=1; //PIT chanel_0 定时器0 （共四个定时器）enabled
PITLD0=9999; //1毫秒 PIT Load Register
PITMTLD0=5; //time-out period = (PITMTLD + 1) * (PITLD + 1) / fBUS
PITMUX=0x00; //0 The corresponding 16-bit timer counts with micro time base 0
PITINTE_PINTE0=1; //PIT Interrupt Enable Register
PITCFLMT_PITE=1; //PIT is enabled
}
//=======速度采集中断函数，已经完全可以采集速度的=========
#pragma CODE_SEG NON_BANKED
void interrupt 66 PIT0Interrupt(void)//测速的中断程序
{
chesudu=PACNT;//车速度值
PITTF_PTF0=1; //定时器1标志位清零
PACNT=0X0000;
}
#pragma CODE_SEG DEFAULT

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