# Airspeed sensor readings all over the place

**URL:** <https://discuss.px4.io/t/airspeed-sensor-readings-all-over-the-place/42122>\
**Category:** PX4 Autopilot\
**Created:** [October 26, 2024, 11:11am UTC](https://discuss.px4.io/t/airspeed-sensor-readings-all-over-the-place/42122 "2024-10-26T11:11:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![virtual\_tours](https://discuss.px4.io/user_avatar/discuss.px4.io/virtual_tours/32/15414_2.png) [@virtual\_tours](https://discuss.px4.io/u/virtual_tours)\
**Post date:** [October 26, 2024, 11:11am UTC](https://discuss.px4.io/t/airspeed-sensor-readings-all-over-the-place/42122/1 "2024-10-26T11:11:29Z")

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Hello

Just got a MS5525DSO airspeed sensor to use it with a holybro pixhawk v6x. The pixhawk is on px4 version 1.15.1. These are the readings I get from the sensor for a stationary device with absolutely no wind (indoors). Blowing into the tube or covering it with my finger doesn’t affect the readings.

 ![Screenshot 2024-10-26 at 3.06.18 PM](https://discuss.px4.io/uploads/default/original/3X/9/9/99827dba91ee51fe1e875d9834f5b88ae1040cda.png)

SENS\_EN\_M5525DS is set to enabled. Calibration either fails due to “Negative pressure”, or it succeeds before I blow into the tube because the sensor believes it received a large enough wind intake (either displays a reading of 100 something or -100 something).

I’ve tried connecting both static and dynamic ports, also tried dynamic port on its own, switched the ports to which the tube connects on the sensor. Basically, all connection combinations have been tried. The sensor is connected to an I2C port on the device.

Am I doing something wrong? or is this simply a faulty sensor?

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**Author:** ![saengphet](https://discuss.px4.io/user_avatar/discuss.px4.io/saengphet/32/3487_2.png) [@saengphet](https://discuss.px4.io/u/saengphet)\
**Post date:** [October 27, 2024, 1:41pm UTC](https://discuss.px4.io/t/airspeed-sensor-readings-all-over-the-place/42122/2 "2024-10-27T13:41:06Z")

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@virtual_tours Hi, I think it is a known issue.

> <https://github.com/PX4/PX4-Autopilot/issues/23434>
>
> \### Describe the bug
> 
> With the Pixhawk 6x + MS5525DSO Airspeed sensor, Master PX…4 FW, the air speed went through calibration, but it did not require blowing into the tube. After going through calibration, the airspeed reading is incorrect & fluctuating.
> 
> No issue with Pixhawk 6C & Pixhawk 4
> 
> !\[image\](https://github.com/user-attachments/assets/f25d2b4f-37cd-4c94-840e-e174df6b93ab)
> 
> 
> 
> \### To Reproduce
> 
> Select VTOL airframe, enable SENS\_EN\_MS5525DS parameter, calibration airspeed sensor, look at airspeed value. 
> 
> \### Expected behavior
> 
> The calibration should require blowing into tube, and sensor reading should be correct after calibration.
> 
> \### Screenshot / Media
> 
> 
> https://github.com/user-attachments/assets/c280fa75-b407-445b-add3-49116b1ec5bd
> 
> 
> 
> \### Flight Log
> 
> N/A
> 
> \### Software Version
> 
> 1.14.3 & Master
> 
> \### Flight controller
> 
> Pixhawk 6X
> 
> \### Vehicle type
> 
> Hybrid VTOL
> 
> \### How are the different components wired up (including port information)
> 
> \_No response\_
> 
> \### Additional context
> 
> \_No response\_

Fixed by this PR

> <https://github.com/PX4/PX4-Autopilot/pull/23650>
>
> \### Solved Problem
> 
> It turns out that the airspeed sensor MS5525DSO (e.g. http…s://holybro.com/products/digital-air-speed-sensor-ms5525dso) uses the same I2C address as the ms5611 potentially connected on the external I2C 3 bus, and so the two conflict and don't work properly.
> 
> Fixes #23434.
> 
> \### Solution
> 
> The suggestion is to just disable the potential external ms5611 for 6X.
> 
> \### Changelog Entry
> For release notes:
> \`\`\`
> Disable external ms5611 on Pixhawk 6x to avoid conflicts with MS5525DSO.
> \`\`\`
> 
> \### Alternatives
> We could also consider disabling it only if \`SENS\_EN\_MS5525DS\` is set to \`1\` but start it otherwise.
> 
> \### Test coverage
> Bench tested.
> 
> FYI @vincentpoont2

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<div class="post-metadata">

**Author:** ![virtual\_tours](https://discuss.px4.io/user_avatar/discuss.px4.io/virtual_tours/32/15414_2.png) [@virtual\_tours](https://discuss.px4.io/u/virtual_tours)\
**Post date:** [October 27, 2024, 7:25pm UTC](https://discuss.px4.io/t/airspeed-sensor-readings-all-over-the-place/42122/3 "2024-10-27T19:25:22Z")

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Thanks, that was it. Installing the main branch fixed it.