/* HC-SR04 Ping distance sensor: VCC to arduino 5v GND to arduino GND Echo to Arduino pin 8 Trig to Arduino pin 9*/ #define echopin 8 // echo pin #define trigpin 9 // Trigger pin int maximumRange = 30; long duration, distance; void setup() { Serial.begin (9600); Serial.setTimeout(50); //Timeout serial if readString is unavailable pinMode (4,OUTPUT); pinMode(2,OUTPUT); pinMode(3,OUTPUT); pinMode(5,OUTPUT); pinMode (trigpin, OUTPUT); pinMode (echopin, INPUT ); } void loop () { int rec; digitalWrite(5,HIGH); digitalWrite(3,HIGH); { digitalWrite(trigpin,LOW); delayMicroseconds(2); digitalWrite(trigpin,HIGH); delayMicroseconds(10); duration=pulseIn (echopin,HIGH); distance= duration/58.2; delay (50); Serial.print("Water tank level: "); Serial.println(distance); } if(Serial.available()>0) { rec=Serial.read(); String inString = ""; inString = Serial.readString(); //Read input string from bolt Serial.print(inString); //Send same string back to bolt } if(rec=='n') { digitalWrite(2,LOW); digitalWrite(4,HIGH); } if(rec=='f'){ digitalWrite(2,HIGH); } if (distance >= 30 ) { digitalWrite(4,LOW); delay (200); } else if (distance < 15){ digitalWrite (4, HIGH); digitalWrite(2,HIGH); delay (200); } }