How to Use Pitot Tube: Examples, Pinouts, and Specs

The TE Connectivity MS4525DO is a digital pressure sensor designed for applications requiring precise measurement of fluid flow velocity. It operates based on the principles of a Pitot tube, which measures the dynamic and static pressure of a fluid to calculate its velocity. This sensor integrates advanced MEMS technology and a digital output, making it ideal for modern electronic systems.

• Aerospace: Airspeed measurement in aircraft
• Automotive: Airflow monitoring in engine systems
• Industrial: Fluid flow measurement in pipelines
• HVAC: Air velocity monitoring in ventilation systems
• Robotics: Environmental sensing for drones and autonomous vehicles

The MS4525DO is a high-performance digital pressure sensor with the following key specifications:

The MS4525DO sensor typically comes in a 6-pin package. Below is the pinout and description:

1. Power Supply: Connect the VDD pin to a 3.3V or 5V power source and the GND pin to ground.
2. Communication Interface: Choose between I²C or SPI communication. For I²C:
   • Connect the SDA pin to the microcontroller's I²C data line.
   • Connect the SCL pin to the microcontroller's I²C clock line.
   • Use the ADDR pin to set the I²C address (pull high or low as needed). For SPI:
   • Connect the SDA pin to the microcontroller's MOSI line.
   • Connect the SCL pin to the microcontroller's SCK line.
   • Use the ADDR/CS pin as the chip select line.
3. Pressure Ports: Attach the Pitot tube to the sensor's pressure ports:
   • The high-pressure port (P1) connects to the dynamic pressure source.
   • The low-pressure port (P2) connects to the static pressure source.
4. Initialization: Configure the microcontroller to communicate with the sensor using the chosen protocol. Refer to the datasheet for initialization commands.

• Ensure the pressure range of the sensor matches your application requirements.
• Avoid exposing the sensor to pressures beyond its rated range to prevent damage.
• Use proper tubing and fittings to minimize leaks and ensure accurate measurements.
• If using I²C, ensure pull-up resistors are present on the SDA and SCL lines.
• Calibrate the sensor periodically for optimal accuracy.

#include <Wire.h>

// Define the I²C address of the MS4525DO sensor
#define MS4525DO_ADDRESS 0x28

void setup() {
  Wire.begin(); // Initialize I²C communication
  Serial.begin(9600); // Start serial communication for debugging
}

void loop() {
  Wire.beginTransmission(MS4525DO_ADDRESS); // Start communication with sensor
  Wire.write(0x00); // Request data from the sensor
  Wire.endTransmission(false); // End transmission but keep I²C active

  Wire.requestFrom(MS4525DO_ADDRESS, 4); // Request 4 bytes of data
  if (Wire.available() == 4) {
    uint8_t byte1 = Wire.read(); // Read first byte
    uint8_t byte2 = Wire.read(); // Read second byte
    uint8_t byte3 = Wire.read(); // Read third byte
    uint8_t byte4 = Wire.read(); // Read fourth byte

    // Combine bytes to calculate pressure and temperature
    int16_t pressure = ((byte1 & 0x3F) << 8) | byte2;
    int16_t temperature = ((byte3 << 8) | byte4) >> 5;

    // Convert raw values to meaningful units
    float pressure_psi = (pressure - 8192) * 0.00390625; // Example conversion
    float temperature_c = (temperature * 0.0977) - 50; // Example conversion

    // Print results to the serial monitor
    Serial.print("Pressure (psi): ");
    Serial.print(pressure_psi);
    Serial.print(" | Temperature (°C): ");
    Serial.println(temperature_c);
  }

  delay(1000); // Wait 1 second before next reading
}

1. No Data from Sensor

   • Cause: Incorrect wiring or communication protocol mismatch.
   • Solution: Double-check the connections and ensure the correct protocol (I²C or SPI) is configured.

2. Inaccurate Readings

   • Cause: Calibration drift or leaks in the pressure tubing.
   • Solution: Recalibrate the sensor and inspect the tubing for leaks.

3. Sensor Not Responding

   • Cause: Incorrect power supply voltage.
   • Solution: Verify that the VDD pin is supplied with 3.3V or 5V as required.

4. Fluctuating Measurements

   • Cause: Electrical noise or unstable pressure source.
   • Solution: Add decoupling capacitors near the sensor and stabilize the pressure source.

Q: Can the MS4525DO measure both positive and negative pressures?
A: Yes, the sensor supports differential pressure measurement, allowing it to measure both positive and negative pressures within its specified range.

Q: Is the MS4525DO waterproof?
A: No, the sensor is not waterproof. Avoid exposing it to liquids or high humidity environments.

Q: Can I use the MS4525DO with a 5V microcontroller?
A: Yes, the sensor is compatible with both 3.3V and 5V systems. Ensure the I²C or SPI logic levels match the microcontroller.

Q: How often should I calibrate the sensor?
A: Calibration frequency depends on the application. For critical measurements, calibrate every 6-12 months or as needed.