Auto-water fountain

Top view of the board showing the Transistor

What is this all about then?

This auto start water fountain was designed for my cat, Huey. I heard animals prefer to drink from a running stream so I was determined to give him one.

The idea is simple; once Huey approaches, the water fountain turns on for 15 seconds.

Ultrasonic sensor

I chose an ultrasonic sensor to measure the distance to the nearest object. It works by sending a high-frequency pulse and waiting for its return. Distance can be calculated by:

D = 1/2 TC

Where:

D is the distance
T is the time in seconds
c is the speed of sound ~ 343 m/s

Other Parts

ESP32 Microcontroller

2N2222A Transistor

4.3k resistor

2-way Quick Connect

5V submersible water pump

Software, C++, Arduino

				
					/*

        Software for an Auto water fountain

        This software is designed to turn on a water pump when an animal approaches the distance sensor.
        It runs for 15 seconds (configurable), then shuts off.

        Dependencies:
          Arduino framework
          ericksimoes/Ultrasonic

*/
#include 
#define GPIO_US1_Trig 12
#define GPIO_US1_Recv 13 
#define GPIO_Pump 25
#define GPIO_LevelMeter 36
#define MaxPumpRunTime 15000                    // 15 Seconds
#define CheckUltrasonicSensorEvery 10           // 10 mS
#define DetectionDistance 25                    // 25 cm

#include 

Ultrasonic MyUltrasonic1(GPIO_US1_Trig, GPIO_US1_Recv); // An ultrasonic sensor HC-04

void setup()
{
  Serial.begin(115200);

  pinMode(GPIO_Pump,OUTPUT);
  pinMode(GPIO_LevelMeter, INPUT);
  digitalWrite(GPIO_Pump,false);          // false=off
}

long Timer_Status=0;          // When millis() exceeds this, print distance to the serial port
long Timer_PumpOff=0;         // When millis() exceeds this, turn the pump off
long Timer_LookForKitty=0;    // When millis() exceeds this, check the UltraSonic sensor

void loop()
{
  long Millis = millis();

  // Turn off the pump if it exceeds the timer
  if(Timer_PumpOff && Millis > Timer_PumpOff)
  {
    digitalWrite(GPIO_Pump, false);
    Timer_PumpOff=0;
    Serial.printf("Turning off pump\n");
  }

  if(Millis > Timer_LookForKitty)
  {
    Timer_LookForKitty = Millis + CheckUltrasonicSensorEvery;

    unsigned int Distance = MyUltrasonic1.read();

    if(Distance <= DetectionDistance)
    {        // Found Kitty
      if(!Timer_PumpOff){                     // Is the pump off? (Haven't Already found kitty)
        Timer_PumpOff = Millis + MaxPumpRunTime;
        digitalWrite(GPIO_Pump, true);
        Serial.printf("Turning ON pump\n");

      }
    }
  }

  // Status Timer controls how often we update the status
  if(Millis > Timer_Status)
  {
    Timer_Status = Millis + 1000;
    //Serial.printf("Dist=%u Water=%d\n",MyUltrasonic1.read(), analogRead(GPIO_LevelMeter));
    Serial.print("Distance=");
    Serial.println(MyUltrasonic1.read());
  }
}