YF-S201C Water Flow Sensor with 1/2 inch threads

Connection

• VIN (Red): You may connect this to 5V pin on arduino UNO but we recommend to connect it to an external power supply of 5V DC
• GND (Black): Connect to GND. Make sure you connect all ground pins together. If you are using an external power supply connect the power supply ground to aduino UNO GND.
• Pulse Output (Yellow): Connect to digital pin 2.

Code

Arduino UNO code for water flow sensor.

No external libraries are needed for this basic code.

#define flowPin 2  // Define the digital pin connected to the flow sensor

volatile int flow_count = 0; // Counts the number of pulses from the sensor

void setup() {
  Serial.begin(9600);        // Initialize serial communication for debugging
  pinMode(flowPin, INPUT);    // Set the flow sensor pin as input
  attachInterrupt(digitalPinToInterrupt(flowPin), flowInterrupt, RISING);
  // Enable interrupt on rising edge (each pulse)
}

void loop() {
  unsigned long currentMillis = millis();
  static unsigned long previousMillis = 0; // Stores time of last interrupt

  // Calculate flow rate every 1 second
  if (currentMillis - previousMillis >= 1000) {
    float flowRate = (flow_count * 60.0) / (currentMillis - previousMillis);  // Flow rate in pulses per minute
    Serial.print("Flow Rate: ");
    Serial.print(flowRate);
    Serial.println(" pulses per minute");
    flow_count = 0; // Reset counter for next measurement
    previousMillis = currentMillis;
  }
}

void flowInterrupt() {
  flow_count++; // Increment pulse counter on interrupt
}