Pixhawk digital airspeed sensor + external compass on I2C Splitter

ArduPlane Plane 3.9
1

Hello,

I just finished my pixhawk installation on a Volantex Ranger EX 757-3

I have an external gps + compass module which works perfectly when plugged in the i2c port directly

I decided to add a digital airspeed sensor so I’m now using an I2C splitter

But with this configuration the external compass is not detected anymore, any idea why it’s not working?

I have the latest arduplane stable release (3.9.8 on ChibiOS)

Also I’m using Qgroundcontrol for the configuration and I tried plugging the airspeed sensor only without splitter and setting the ARSPD_PIN to 65 but I don’t see any data related to airspeed on the interface or any new sensor, how can I check that it’s working?

2

It might be an I2C address conflict but have you tried as they suggest
“Note: if you can’t use the item, please change SDA->SCL,and SCL->SDA”

Have you also
" You need to enable the airspeed sensor in Mission Planner | Hardware | Optional Hardware | Airspeed ."
As mentioned in the docs here

3

I’m not using mission planner, I’m using QGroundControl (I’m on linux)

But I set the option ARSPD_USE to 1 and ARSPD_TYPE to I
2C-MS4525D0 both are correct for this airspeed sensor

I’ll try to switch the cables if needed but I’d like to know first where can I see the airspeed data in Qgroundcontrol because maybe it’s working but I have no idea

Here are the airspeed related settings

Screenshot_20190610_143459
Screenshot_20190610_143459.png728×835 107 KB

4

Disconnect the compass from the splitter and see if you get airspeed readings. If so you have a weird address conflict. Compass and Airspeed are usually on different addresses.

The most likely explanation is a bad cable connection though.

Not sure about QGC as I use MP. But airspeed should be very visible.

5

Only way to know if working ok is to probe the module with an I2C tool

As with conflicting I2C bus, I experienced some issues with termination resistors on a star configuration, in a particular case I had to daisy-chain the modules

6

I’m currently only testing without the splitter, I can’t get the airspeed sensor to work, the cables were completely wrong… The 5v cable was on the clock and vice versa. I put them back how they should be but still nothing…

Any chance I fried it by getting a wrongly mapped cable?

7

You can probe with a Raspberry Pi or an Arduino that would really tell if this module is working or not

8

Hi, Adrien
I have the same problem, as you solved it?
Thank you

9

I think you may have killed it. I did the same thing with a bad ebay cable and it never worked again after that. Not sure those pins are 5v tolerant.

10

I’m pretty sure that’s what happened yes, I haven’t ordered a new one but got a refund

I remember it was very hot after this (in the 80°C range)

So I think that killed it, I’d have to make sure with a new one