The YF-S201 G1/2" DN15 Water Flow Sensor is a Hall-effect based flow meter designed for accurate and real-time water flow measurement. It is commonly used in water dispensers, irrigation systems, coffee machines, and smart water monitoring solutions. The sensor generates digital pulse signals proportional to the flow rate, making it easy to interface with microcontrollers like Arduino, ESP32, Raspberry Pi, and STM32.

Working Principle:

The sensor consists of a magnetic core, rotating impeller, and a Hall-effect sensor. When water flows through the sensor:

1. The impeller rotates, triggering the magnetic core.

2. The Hall-effect sensor detects the rotation and outputs a pulse signal.

3. The number of pulses per second corresponds to the water flow rate.

4. The flow rate is calculated using the formula:

   $$\text{Pulse Frequency}=\text{Flow Rate (L/min)}\times 7.5$$

   For example, if the pulse frequency is 75Hz, the water flow rate is:

   $$75÷7.5=10\text{ L/min}$$

Specifications:

Features:

• High Accuracy: Converts water flow into digital pulses for precise measurement.
• Wide Voltage Range: Operates on 5V to 24V, making it compatible with various systems.
• Compact & Lightweight: Weighs only 43g, making it ideal for embedded applications.
• Easy Interface: Works with Arduino, ESP32, Raspberry Pi, and STM32 with minimal setup.
• Durable Build: Handles liquid temperatures up to 80°C and water pressure up to 1.75 MPa.

Applications:

• Water flow monitoring in coffee machines, water dispensers, and vending machines.
• Irrigation systems for precise water control.
• Smart water meters for home automation and IoT projects.
• HVAC (Heating, Ventilation, and Air Conditioning) systems.
• DIY electronics projects using Arduino, ESP32, and Raspberry Pi.

The YF-S201 water flow sensor is a Hall-effect sensor that measures the flow rate of water in liters per minute (L/min). It is widely used in water dispensers, irrigation systems, and other fluid monitoring applications.

Components Required:

• Arduino Uno (or any compatible board)
• YF-S201 Water Flow Sensor (G1/2" DN15)
• 10kΩ pull-up resistor (optional)
• Jumper wires
• 5V Power supply (Arduino’s 5V pin)

Wiring Diagram:

Notes:

• The signal wire (yellow) outputs pulses corresponding to the water flow rate.
• A 10kΩ pull-up resistor can be connected between the signal (yellow) and VCC (5V) for more stable readings.
• Ensure the arrow direction on the sensor is aligned with the flow direction.

Arduino Code:

volatile int pulseCount = 0;
float flowRate = 0.0;
unsigned long oldTime = 0;

void IRAM_ATTR pulseCounter() {
    pulseCount++;
}

void setup() {
    Serial.begin(9600);
    pinMode(2, INPUT_PULLUP);
    attachInterrupt(digitalPinToInterrupt(2), pulseCounter, FALLING);
}

void loop() {
    if (millis() - oldTime > 1000) {  // Update every second
        oldTime = millis();

        // Flow rate formula: (Pulse Count / 7.5) = Flow Rate in L/min
        flowRate = (pulseCount / 7.5);

        Serial.print("Flow Rate: ");
        Serial.print(flowRate);
        Serial.println(" L/min");

        pulseCount = 0;  // Reset pulse count
    }
}

How It Works

• The Hall sensor in YF-S201 generates pulses as water flows through it.
• The Arduino interrupt (pin 2) detects these pulses.
• The program counts pulses and calculates the flow rate using the formula: Flow Rate(L/min)=Pulse Count7.5\text{Flow Rate} (\text{L/min}) = \frac{\text{Pulse Count}}{7.5} (The value 7.5 is an empirical constant provided by the sensor manufacturer.)
• The result is displayed on the Serial Monitor.