//继电器高电平闭合，低电平断开
const int relay1=21;//继电器1信号引脚和IO21连接
const int relay2=19;
const int relay3=18;
const int relay4=5;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);//设置串口显示波特率115200
  Serial.println("start test the electric relay the circuit···");
  pinMode(relay1, OUTPUT);//设置relay1脚为输出状态
  pinMode(relay2, OUTPUT);
  pinMode(relay3, OUTPUT);
  pinMode(relay4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(relay1,HIGH);//高电平闭合，亮
  delay(random(1000)); // this speeds up the simulation
  digitalWrite(relay1,LOW);//低电平断开，灭
  delay(random(1200+random(400)));
  Serial.println(random(1200+random(400)));

  digitalWrite(relay2,HIGH);
  delay(random(1000)); // this speeds up the simulation
  digitalWrite(relay2,LOW);
  delay(random(1200+random(400)));
  Serial.println(random(1200+random(400)));

  digitalWrite(relay3,HIGH);
  delay(random(1000)); // this speeds up the simulation
  digitalWrite(relay3,LOW);
  delay(random(500+random(400)));
  Serial.println(random(500+random(400)));

  digitalWrite(relay4,HIGH);
  delay(random(1000)); // this speeds up the simulation
  digitalWrite(relay4,LOW);
  delay(random(1200+random(400)));
  Serial.println(random(1200+random(400)));

}