// Automatic watering system for larger potted plants using an arduino, relay, and water pump. #define RELAY1 7 const int hygrometer = A0; //Hygrometer sensor analog pin int value; void setup() { pinMode(RELAY1, OUTPUT); digitalWrite(RELAY1, HIGH); delay(2000); //wait 2 seconds before starting the loop } void loop() { // When the plant is watered well the sensor will read a value between 380~400 value = analogRead(hygrometer); //Read hygrometer value value = constrain(value,400,1023); //Keep the ranges! value = map(value,400,1023,100,0); //Map value : 400 will be 100 and 1023 will be 0 //Start the watering if humidity drops below 20% if (value < 20){ digitalWrite(RELAY1,LOW); // Turns the Relay/Pump on } else { digitalWrite(RELAY1,HIGH ); // Relay/Pump is off } delay(250); //delay a quarter of a second }