Pixracer: Potential power sequencing issue on GPS port

[pixhawk]

Pixracer: Potential power sequencing issue on GPS port

[LorenzMeier]

So it seems like connecting battery "kills" the sensor. Which seems absurd.

Maybe the device went into a bad state when we powered it reverse.

[RomanBapst]

Correct, having usb connected the driver works. Connecting power without even removing the usb cable kills the driver.

[pkocmoud]

Power Up using Battery, connecting and disconnecting USB, Battery remains connected until the end.

[LorenzMeier]

@pkocmoud It would be great if you could try to repro with one of these: http://www.hobbyking.com/hobbyking/store/%5F%5F62752%5F%5FHKPilot%5F32%5FDigital%5FAir%5FSpeed%5FSensor%5FAnd%5FPitot%5FTube%5FSet.html

[pkocmoud]

"repro"? I have the 3DR Version to test with.

[RomanBapst]

@pkocmoud That would be great.

[pkocmoud]

Recorded while loaded with Master.

[pkocmoud]

No Brown Outs Detected. The PixRacer power supply is solid during our tests.

[LorenzMeier]

@Tumbili If you comment out this line, does it work for you?
https://github.com/PX4/Firmware/blob/0e0c1302e41abc75e83bd3b0a324bead952f8a16/src/drivers/meas_airspeed/meas_airspeed.cpp#L228

[RomanBapst]

@LorenzMeier same thing

[LorenzMeier]

Odd. It has to be somewhere there.

[LorenzMeier]

So my 2nd board has an all working sensor. We have now 3 boards:

1): 0-1.8V on the 5V rail
2): Romans board: 5V on GPS rail, but no airspeed sensor signal when powered via the 3DR power module
3): Completely working when powered at 5.3V through a lab power supply

The only thing I haven't tried yet is what happens when the sensing / ADC pins are active, as I have no power module.

I certainly have a bad board, not sure yet about the causality of the other two items.

[RomanBapst]

@LorenzMeier Is 5.3 a magic value? Does is also work with 5V?

[LorenzMeier]

Your power module is outputting 5.3V. Which is why I chose it.

[nickarsov]

Yes, it works with 5V too, because the USB can't supply 5.3V

[LorenzMeier]

Nick, rather than speculating it would be good if you could work out how I can return the electrically bad board to your for inspection.

[nickarsov]

Lorenz,
Speculating with what...I just answered to Roman.
And yes, you can return it back to me for inspection at:
Nick Arsov
8 Konstantin Irechek str., bl.1
4700 Smolyan
Bulgaria

[LorenzMeier]

Thanks, will do! I'm closing this as it seems board-specific.

[LorenzMeier]

@nickarsov the part you identified has 5V on one side and 0V on the other.

[LorenzMeier]

Soldering looks sketchy. I will rework it later today or tomorrow.

[LorenzMeier]

This was in fact the airspeed sensor. Still have one board with 1.8V on that port, but that is probably manufacturing QA. Replaced with: #55