有没有大佬能解释一下

#include <MsTimer2.h> //定时中断

#define E1 11 //超声波
#define T1 12

#define E5 7 //超声波
#define T5 8

#define E4 A0 //超声波
#define T4 A1

#define E2 A2 //超声波
#define T2 A3

#define E3 A4 //超声波
#define T3 A5

#define M1 5 //舵机
#define M2 6
#define M3 9
#define M4 10


int signal_beep = 2; //信号输入

int signal_beep_1 = 3;
unsigned int Front_Distance;//超声波检测距离
unsigned int Front_Distance_1;//超声波检测距离
unsigned int Right_Distance;//超声波检测距离
unsigned int Left_Distance;//超声波检测距离
unsigned int Back_Distance;//超声波检测距离
int time_cnt = 0;
int cnt = 0;

void setup()
{
pinMode(M1, OUTPUT);//端口设置
pinMode(M2, OUTPUT);
pinMode(M3, OUTPUT);
pinMode(M4, OUTPUT);
pinMode(signal_beep, INPUT);
pinMode(signal_beep_1, INPUT);
pinMode(E1, INPUT);
pinMode(T1, OUTPUT);

pinMode(E2, INPUT);
pinMode(T2, OUTPUT);
pinMode(E3, INPUT);
pinMode(T3, OUTPUT);
pinMode(E4, INPUT);
pinMode(T4, OUTPUT);
pinMode(E5, INPUT);
pinMode(T5, OUTPUT);
delay(100);