Matek Digital Airspeed Sensor ASPD-4525 (MS4525DO) with Pitot Tube

Specifications

• Sensor: MS4525DO (Measurement Specialities).

• Type: Differential Pressure Sensor (Digital).

• Pressure Range: 1 psi (approx. 100 m/s or 360 km/h top speed).

• Interface: I2C (SCL/SDA).

• Input Voltage: 4V - 6V DC.

• Board Dimensions: 20mm x 20mm.

• Weight: ~5g (Board only).

Compatibility & Platform Support

• ArduPilot: Native Support. Select ARSPD_TYPE = 1 (MS4525DO). Essential for auto-throttle and VTOL transitions.

• INAV: Supported. Enables "Air Mode" and stall prevention warnings on the OSD.

• Flight Controllers: Works with any FC running ArduPilot/INAV with an available I2C port (Matek F405-SE, H743-WING, SpeedyBee F405 Wing, etc.).

Key Applications & Projects

• VTOL Builds: Absolutely mandatory for QuadPlane/VTOLs to manage the transition from hover to forward flight safely.

• Long Range Efficiency: Allows the autopilot to fly at "Best Efficiency" speed (cruise) rather than a fixed throttle percentage, saving battery.

• Windy Conditions: Helps the autopilot throttle up automatically when flying into a headwind to maintain lift.

Virtual Technician: Wiring & Safety ⚠️

• Tubing Installation: The kit includes two tubes. Connect the Straight part of the Pitot tube (Dynamic Pressure) to the Top port of the sensor. Connect the Angled part (Static Pressure) to the Bottom port.

• I2C Addresses: The sensor usually has a default address. If you use multiple I2C devices (like a Compass), ensure they don't clash (Compass is usually 0x1E, Airspeed is different).

• Calibration: Before the first flight, perform the "Pre-Flight Calibration" in Mission Planner to zero out the sensor while the pitot tube is covered (no wind).

Accessories

• Included in the Package:

  • 1 x Matek ASPD-4525 Sensor Board

  • 1 x Metal Pitot Tube

  • 1 x Silicon Tubing (~40cm)

  • 1 x JST-GH to JST-GH Cable (20cm)

Frequently Asked Questions (FAQ)

1. Why do I need an airspeed sensor if I have GPS? GPS only measures speed over the ground. An airspeed sensor measures how fast air is moving over your wings. This prevents Stalls (flying too slow relative to the air) and helps in windy landings.

2. Is this compatible with INAV? Yes, INAV fully supports the MS4525DO. It allows for True Airspeed display on the OSD and wind speed estimation.

3. What ArduPilot parameter do I use? Set ARSPD_TYPE to 1 (MS4525DO) and ARSPD_BUS to 0 (or 1 depending on which I2C port you use).

4. How do I connect the tubes correctly? The Top Nipple on the sensor connects to the Straight Tube (Dynamic Pressure/Front hole). The Bottom Nipple connects to the Angled Tube (Static Pressure/Side holes).

5. What happens if I swap the tubes? Your airspeed reading will be negative or zero. If you see negative speed when blowing into the tube, swap the hoses.

6. Does it require calibration? Yes. You must perform a "Pre-Flight Calibration" in your Ground Control Station (Mission Planner/INAV) before every flight to zero the sensor offset.

7. What is the maximum speed it can measure? The 1 PSI sensor can measure up to approximately 100 m/s (360 km/h), which is sufficient for almost all hobby drones.

8. Is this sensor waterproof? No. The sensor chip is open to the air. If water enters the pitot tube and reaches the sensor, it will fail. Do not fly in heavy rain.

9. Can I cut the silicone tubing? Yes, you can cut the tubing to fit your fuselage. Ensure you don't kink or pinch the tubes, as this will block the airflow.

10. Where should I mount the pitot tube? Mount it on the nose or the leading edge of the wing, far away from the propeller wash. Propeller airflow will give false high readings.

11. Why is my airspeed reading fluctuating on the bench? Sensitive pressure sensors react to drafts from AC units, fans, or even opening a door. Cover the tip of the pitot tube to see if it stabilizes to zero.

12. Does it work with SpeedyBee Wing controllers? Yes, as long as the flight controller has an I2C Pad (SDA/SCL) and 5V/4.5V power, it will work.

13. Is this better than the Analog version? Yes. Digital (I2C) sensors are immune to electrical noise and voltage drops, making them much more accurate than older analog sensors.

14. What voltage does it need? It operates on 4V to 6V DC. Connect it to the 4V5 or 5V pad on your FC. Do not connect to VBAT!

15. Can I use this on a Quadcopter? Generally no. Quadcopters don't need airspeed for lift. It is strictly for Fixed-Wing planes and VTOLs.

16. How do I test if it's working? Gently blow (from a distance) onto the tip of the pitot tube. You should see the airspeed value in Mission Planner rise. Do not use compressed air, it will burst the sensor diaphragm.

17. What happens if the tube gets clogged? The sensor will read 0 airspeed. If in auto mode, the plane might dive or throttle up dangerously to try and gain speed. Always check for bugs/dirt before flying.

18. Does it support "Auto Calibration"? ArduPilot has an ARSPD_AUTOCAL feature that can calibrate the ratio during flight, but a pre-flight zero is still recommended.

19. What is the I2C address? The default I2C address for MS4525DO is usually 0x28.

20. Is the cable included compatible with Pixhawk? The included cable is usually JST-GH (common on Matek/Cube). Older Pixhawks might use Molex PicoBlade, so check your connector type.