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 10int 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);