程控小车PWM加减速

/* =======直流电机的PWM速度控制程序======== */ 
/* 晶振采用11.0592M,产生的PWM的频率约为91Hz */ 
#include<reg51.h> 
#include<math.h> 
#define uchar unsigned char 
#define uint unsigned int 
sbit en1=P2^0;  /* L298的Enable A */ 
sbit en2=P2^1;  /* L298的Enable B */ 
sbit s1=P2^2;  /* L298的Input 1 */ 
sbit s2=P2^3;  /* L298的Input 2 */ 
sbit s3=P2^4;  /* L298的Input 3 */ 
sbit s4=P2^5;  /* L298的Input 4 */ 
uchar t=0;   /* 中断计数器 */ 
uchar m1=0;   /* 电机1速度值 */ 
uchar m2=0;   /* 电机2速度值 */ 
uchar tmp1,tmp2; /* 电机当前速度值 */ 

/* 电机控制函数 index-电机号(1,2); speed-电机速度(-100―100) */ 
void motor(uchar index, char speed) 
{ 
 if(speed>=-100 && speed<=100) 
 { 
  if(index==1) /* 电机1的处理 */ 
  { 
   m1=abs(speed); /* 取速度的绝对值 */ 
   if(speed<0) /* 速度值为负则反转 */ 
   { 
    s1=0; 
    s2=1; 
   }