Hello guys,

today I tried out the airspeed sensor with my new Atmega 2560 board. I used the MPXV7002Dp airspeed sensor.

 I wanted to test it, in test mode, but it only displayed "airspeed: disabled". I then checked the voltages of the airspeed sensor with this post, checked my cable etc. Everything seemd to work just fine, only that the measured voltages always where to low. The measured supply voltage was 4.7 V (I measured at the connector between 5V and Gnd). Also the suplly voltage on the Atmega (i measured on the back of the board between 5V and Gnd) was also only 5V. The However the ESC supllied the board with 5V.

With the Voltage beeing to slow but the airspeed sensor working, i just changed the code in 2 places: One time in "test.pde"

 

test_airspeed(uint8_t argc, const Menu::arg *argv)
{
if (adc.Ch(AIRSPEED_CH) > 2600)              //Changed this from 2900 to 2600
...

 

and the "System.pde"

 

 if (adc.Ch(AIRSPEED_CH) > 2600 || HIL_MODE != HIL_MODE_DISABLED) {      //Also changed the Threshold from 2900 to 2600

 

After this it worked fine (a picture with a test is attached). The Threshold was just too high, for such a low supply voltage.

One of my colleges meant that the supply voltage might be too low because of an diode, between the servo rail and the 5V supply of the shield, but I dont know exactly.

What also came up is that the scaling of the windspeed could be wrong, because of the low supply voltage

 

Did anyone else have the same? Or is my board damaged?

 

Thank you

 

Phil

 

airspeedsensortest.png

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Replies

  • I've seen several discussions about the auto-detection of the different versions of airspeed sensor. I'm unsure if an issue has been opened but it seems the threshold of >2900 does not apply to all of the sensors that people have. Your hardware is probably fine. In my case I've had to change it to <2800 because I get higher values when it is not connected.
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