Airspeed Sensor ​​on APM 2.012 does not work

John May 2, 2011 at 11:26pm

Just tested APM2.1 and the airspeed sensor works when auto detedting.

Thaks all for the great work!!!

John May 1, 2011 at 9:38am

Hi All

After testing the change in code I noticed that the airspeed sensor was still enabled even if it was disconnected.

I am testing with a MPXV7002DP Airspeed sensor.

I have changed the code again and now the airspeed sensor is enabled when connected and disabled when not connected.

I have no clue with coding , only a little common savvy. so you are all welcome to shoot me down, but this seems to work so far for me. I only changed the auto detect lines in system.pde as follows

// Autodetect airspeed sensor

if (adc.Ch(AIRSPEED_CH) < 2900) //Air speed sensor not detecting, Changed > 2900 to <2900

{

airspeed_enabled = false; //Air speed sensor not detecting, Changed true to false

}

else

{

airspeed_enabled = true; //Air speed sensor not detecting, Changed false to true

}

Cheers!

John

John May 1, 2011 at 12:56am

Hi All

I also had the problem of the airspeed sensor not being detacted and displaying disabled when testing in CLI. I only changed the auto detect lines in system.pde as follows

// Autodetect airspeed sensor

if (adc.Ch(AIRSPEED_CH) > 2900)
{
airspeed_enabled = true;
}
else
{
airspeed_enabled = true;// changed from false to true. Airspeed sensor was not auto detecting.
}

Now the airspeed sensor works all the time.
I will keep testing it to see if it stays that way.

Thanks for the good work all.
John

Mikko Saarisalo April 30, 2011 at 2:05pm

I just checked both of the data sheets and t seems that their sensitivities are in deed different.

Older MPXV5004DP: Output voltage goes from 1.0V to 5.0V for the pressure range from 0 to 4.0 kPa. Sensitivity 1V/kPa

Newer MPXV7007DP: Output voltage goes from 0.5V to 4.5V for the pressure range from 0 to 7.0 kPa. Sensitivity 286 mV/kPa

(Hope I did read all the numbers correctly)

The outcome without sensor detection explains the observed problem and readings but also would require a different transfer function for the sensor raw value readings.

Datasheets attached.

cheers
-mikko

MPXV7007.pdf

MPXV5004G.pdf

Arve Tokheim April 26, 2011 at 3:19pm

Hi guys. I have the MPX5004DP pressure sensor as well and experienced this same issue. I'm very glad I came accross this thread, thanks for your advices! I have now changed the code by removing the detection test, and the airspeed sensor is now up and running. My only concern is whether the MPX5004 sensor needs to be recalibrated? Or should they output the same measurement data? When testing on ground it looks good though (readings in the interval of 0 to 1.41m/s)

Mikko Saarisalo April 26, 2011 at 7:02am

Hi guys,

I also have MPXV500 airspeed sensor (well - two of them...) - both from DIYDrones Store.

I am getting 1420..1440 when the sensor is connected and 2550..2790 when the sensor is not connected. (A handful of samples for both cases, ambient temp 25°C)

My oilpan version is HOTEL 1.0 and APM is ATMEGA1280 from Sparkfun and has the channel markings reading from IN0..IN7 and OUT0..OUT7.

Should I write an issue report about this?

cheers
-mikko

3D Robotics

Chris Anderson April 10, 2011 at 12:32pm

The airspeed sensor is autodetected in APM 2.012. It works on all of ours, so the question is why isn't yours being detected? One thing I note is that you're not using the recommended airspeed sensor (http://store.diydrones.com/Kit_MPXV7002DP_p/kt-mpxv7002dp-01.htm). Where did you get your sensor?

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Airspeed Sensor on APM 2.012 does not work

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