I2C splitter board needed

Hi there,

So Adam gave me the info to connect the temp sensor in to the BR2 but the issue is that the pixhawk was already pre-installed and i did not get the rest of the spare parts with it. So the I2C splitter board is the component that i do not have which is what Adam says i should use to plug the bar30 and temp sensor into. This is not something that i can source in NZ anytime soon.

Any thought as to how i can sort this issue?


The I2C splitter board breaks out all of the I2C lines in parallel to several connectors. You can hook up multiple I2C devices manually by connecting all of the I2C lines in parallel. There is currently no driver for the Celsius temperature sensor on the Pixhawk, but it is on the agenda. In the meantime, the Bar30 provides a (less accurate) temperature measurement. You can view the Bar30 temperature measurement in the SCALED_PRESSURE2 field from the mavlink inspector widget in QGC.


Hi Kaos,

It looks like some of the more recent Pixhawk accessory packages we have been including with the BlueROV2 have not been coming with the I2C splitter boards. You can make a note about the splitter on your next order, and we can toss one of our spare ones into the package for you.


Any update on when the Celsius sensor will be supported on the BlueROV2 setup?

I’ve added support in the code, but no compiled binaries are up. It will be included in the next stable release, we’re aiming for sometime in March for that.

If there is interest in using the development version of the firmware, I can provide it.


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Thanks. If you have a development build I wouldn’t mind trying. We will only be testing it lightly until spring anyway, mostly on bench. I have the ROV apart now and was going to update all the software anyway so be open to trying the latest and greatest both for Pixhawk and Pi if its available.

Latest development build is up: http://firmware.ardusub.com/Sub/2017-02/2017-02-01-12%3A45/
With this firmware, you should see a new ‘Frame’ tab in the ‘Vehicle Setup’ view in QGC >= 3.1.0.
If a Celsius sensor is connected, the temperature reading will appear in SCALED_PRESSURE3.


Thanks Jacob,
I will try this when the splitter board turns up.

Hi Jacob,
I got the temperature sensor wired in and running with output in mavlink inspector for scaled pressure 2 and 3.
I would like to see the Temps in a widget on screen and log temp/depth together for analysis after the dive. A graph analysis showing depth and temperature change. Is that possible?
I also found QGC would crash or hang when I clicked on the camera tab. Connection randomly dropped out at times as well. Also comes up with warning which is persistent on screen over other information.
I would attach a couple of screen shots but there is no attachment icon showing in this dialogue screen

You can just drag images into the message as you compose it.

I have a patch for this. I will ask the QGroundControl guys to pull it in when I can test it some more.

Yes, there are some tools available to analyze logs, I only have experience using MAVExplorer and Mission Planner. QGC will let you ‘replay’ a log, but it’s not really useful for analyzing or post-processing flight data.

There has been a recent change in parameter names in the autopilot code that QGC has not caught up with yet. The RC_ parameters in the autopilot firmware that QGC wants to configure in the camera tab no longer exist on the autopilot if you are using the latest development branch of the autopilot firmware.


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Thanks Jacob,
You gave me plenty to smile about :grin:
The BR2 is developing quickly into an industry leader open source tool, thanks to people such as yourself n BR team.:thumbsup:
I’m not a coder but if I can help with development in any way, let me know.

I just received my ROV2 with 200m of cable this Thursday (YAY!).
I also need to add the Temperature sensor along with depth.
Were we supposed to ‘ask’ for the extender board or should that have come with the full kit?
how do I acquire the I2C extender board!

The I2C extender board should be in the box with your Pixhawk. There will be a bunch if accessories in there you will need for the build.

I only received the i2C voltage converter, not a splitter. :frowning:

@maleche1, shoot an email to support@bluerobotics.com, and we can get you one.


I just got the i2C rapid temperature sensor and installing it along with the underwater GPS. Just wondering if you need something other than the i2C splitter to plug it in to the pixhawk? I’m left a little confused because there is no third wire to run from the splitter to the actual board. There’s also no image or schematic that I can see that details how this ends up looking, would it be possible for someone to grab a snap of it and share it so we can see?

The i2c splitter is all you need (assuming you are using an i2c depth sensor as well).

Do you have our Celsius temperature sensor in a penetrator, or just the Celsius pcb? It’s not clear what ‘third wire’ you are referring to.

Hi Vincent,

I believe I know what you are referring to. By default, the Bar30 plugs directly into the Pixhawk. When using the splitter board, Both the Bar30 and Celsius plug into the splitter board instead- however the board has all female DF13 connectors. Thus you need a third male to male DF13 cable to plug the splitter board into the Pixhawk. There should have been a cable like this included with your BlueROV2, along with the splitter board in the Pixhawk accessories package. Are you missing this cable?


Yes, Adam you’ve explained that better than I have. I’m missing the male to male connector, it doesn’t appear to be in the bag of pixhawk goodies.

Jacob, this is with the rapid temperature sensor in penetrator version.

Hi Vincent,

Okay, send us an email at support@bluerobotics.com, and we’ll send one out- it should have been included.