How to Use waterproof ultrasonic sensor: Examples, Pinouts, and Specs

The JSN-SR04T is a waterproof ultrasonic sensor designed to measure distances or detect objects using ultrasonic waves. Its waterproof design makes it ideal for applications in wet or harsh environments, such as outdoor installations, liquid level measurement, and industrial automation. This sensor is particularly useful in scenarios where traditional ultrasonic sensors may fail due to exposure to moisture or water.

• Liquid level measurement in tanks or reservoirs
• Obstacle detection in outdoor robotics
• Parking assistance systems
• Industrial automation in wet environments
• Smart irrigation systems

The JSN-SR04T is a robust and reliable sensor with the following key specifications:

The JSN-SR04T module has a 4-pin interface for easy integration into circuits. Below is the pinout:

1. Power the Sensor: Connect the VCC pin to a 5V DC power source and the GND pin to the ground.
2. Trigger the Sensor: Send a 10µs TTL pulse to the Trig pin to initiate a measurement.
3. Read the Echo: Measure the width of the pulse on the Echo pin to calculate the distance. The pulse width is proportional to the distance of the detected object.
4. Distance Calculation: Use the formula below to calculate the distance: [ \text{Distance (cm)} = \frac{\text{Pulse Width (µs)}}{58} ]

• Ensure the sensor is powered with a stable 5V DC supply to avoid erratic readings.
• Avoid placing the sensor near ultrasonic noise sources, as this may interfere with its operation.
• The sensor is waterproof, but the module itself (PCB) is not. Protect the module from water exposure.
• Use a pull-down resistor on the Echo pin if the signal is unstable.
• For best results, ensure the sensor is mounted perpendicular to the surface being measured.

Below is an example of how to connect and use the JSN-SR04T with an Arduino UNO:

// Example code for JSN-SR04T with Arduino UNO
// This code measures distance and prints it to the Serial Monitor

#define TRIG_PIN 9  // Define the Trig pin
#define ECHO_PIN 10 // Define the Echo pin

void setup() {
  pinMode(TRIG_PIN, OUTPUT); // Set Trig pin as output
  pinMode(ECHO_PIN, INPUT);  // Set Echo pin as input
  Serial.begin(9600);        // Initialize serial communication
}

void loop() {
  // Send a 10µs pulse to the Trig pin
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Measure the duration of the Echo pulse
  long duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate the distance in cm
  float distance = duration / 58.0;

  // Print the distance to the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  delay(500); // Wait for 500ms before the next measurement
}

1. No Output or Incorrect Readings

   • Cause: Insufficient power supply or loose connections.
   • Solution: Ensure the VCC pin is connected to a stable 5V source and all connections are secure.

2. Unstable Distance Measurements

   • Cause: Electrical noise or interference from nearby devices.
   • Solution: Use a decoupling capacitor (e.g., 100µF) across the VCC and GND pins to stabilize the power supply.

3. Sensor Not Detecting Objects

   • Cause: Object is outside the sensor's range or has poor ultrasonic reflectivity.
   • Solution: Ensure the object is within the 20cm to 600cm range and has a surface that reflects ultrasonic waves effectively.

4. Echo Pin Always HIGH or LOW

   • Cause: Faulty sensor or incorrect wiring.
   • Solution: Verify the wiring and test the sensor with a different microcontroller or circuit.

Q: Can the JSN-SR04T measure distances underwater?
A: The sensor head is waterproof, but it is not designed for underwater distance measurement. It works best in air.

Q: How do I protect the module (PCB) from water?
A: Use a waterproof enclosure for the module while leaving the sensor head exposed.

Q: Can I use the JSN-SR04T with a 3.3V microcontroller?
A: The sensor requires a 5V power supply, but you can use a level shifter to interface the Trig and Echo pins with a 3.3V microcontroller.

Q: What is the maximum cable length for the sensor head?
A: The sensor head comes with a pre-attached cable. Extending the cable may degrade performance due to signal loss. Use shielded cables if extension is necessary.