SDP3x Not Working (Cross Posted Here)

Need some help to figure this one out:

Pixhawk 2.1 Cube (Black)
Firmware 3.9.10
MP version 1.3.68
Nimbus 1800 VTOL airframe
Using an I2C expansion board
Using Here GPS
Using Motor/ESC combos that Foxtech uses (version 2 setup)
Mauch PL series current sensor with Mauch BEC (which is also giving me problems)
Power supply is a 6S 8000maH 10C
It’s not fully configured and it has never hovered or flown yet
GPS, Radio, Magnetometer and Accelerometers are calibrated and work fine until I try to use this sensor

Full Parameter File Here: Nimbus VTOL V1.param (17.0 KB)

Problem: I have an SPD3x airspeed sensor that will not work (will not report any airspeed changes)
What I’ve diagnosed so far:

  1. I used a multi-meter to confirm pin outs on both nose and body and those appear to be lining up correctly as follows: Nose side - + D1 D2 match body side - + D1 D2 and the pin outs of the SPD3x are - is Positive Volts, + is SCL, D1 is SDA and D2 is Ground.

Color scheme is as follows:

  1. If I use a regular JST-GH connector (like the one that comes with the SPD3x and plug the SPD3x directly into the I2C port on the PH2.1 (and thus removing any possibility that it is a body to nose cable problem) IT DISABLES the GPS! By disable I mean it looks like it is browning out the whole HERE GPS unit and no GPS gets to Mission Planner. Again, this is by doing a direct connect with a normal connector shown below that I bought a 10 pack of back in the day:

  1. Due to the airframe design I am unable to have the SPD3x connected during bootup and I do not know if that is a problem or not.

  2. In case it matters I hooked up the ESCs and servos according to this and I have not proven if it is correct yet as I want everything else to be working first:

It is configured as shown below:


And shows this on the HUD:

I have used this sensor before on a previous VTOL build and after changing the ARSPD Bus variable to 0 it worked perfectly. A comparison of the parameters between that working airframe and this one reveals no help.

Here she is so far:

I’m stumped!!

did you solve this problem?

If I recall correctly, the problem was that the wires came out of the sensor as 1234, but when you hook them into the auto pilot they had to be 4321. There was one or two wires that needed to be swapped. It was very easy to overlook.