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Bar02 is not showing any readings

I have purchased a Bar02 pressure sensor and I am using it for depth calculation in our ROV. I am trying to test the sensor with a Arduino UNO and i am running the example sketch given on Blue Robotics website. There is a weird problem that i am facing, after uploading the code in Arduino when i check the serial monitor i am not getting any data. I have also purchased a Celsius sensor from Blue Robotics and it is working fine and i am getting proper readings both under water and above water. We are a team of second year engineering students trying to build a ROV, please help us out with this issue.


Are you using logic level converter between the sensor and the Arduino ?
The Bar02 sensor uses 3.3V I2C, and the arduino output is 5V.

Hi Patrick,
Well actuall I am not using logic level converter, but i am using 3v3 pin in arduino for power pin.
Is this actually causing the problem?


Yes, that can cause the problem and can damage the sensor.
The arduino microcontroller has 5V I/O and the sensor is 3.3VI/O and can accept a power supply up to 5.5V.
You can check that in the learn tab in the sensor page.

You can read more about that here:

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Thank you so much, yes this is the problem.
But one more thing, i hope this is not a case with Celsius sensor.
Will I need to use a logic level converter with it as well?
It is working fine right now, I don’t want to put it to risk as well.


Both sensors uses 3.3V I/O as you can see in the documentation.
If the sensor is connected in a 5V I/O microcontroller, and works, it can be damaged after some time in this condition.

Thank you so much. I’ll surely keep it mind. This was really helpfull.

Also please tell me if i am connecting Bar02 with Pixhawk, will i have to use the logic level converter for interface between pixhawk and the sensor? I am asking this because the Pixhawk provides 5v on the I2C power line as well.


Again, as the documention says here.

The sensor communicates over I2C. It operates on 3.3V I2C voltage but can accept power input up to 5.5V. It comes standard with a 4-pin DF13 connector that is compatible with most DroneCode compatible boards including the APM2.6, PixHawk, and others.

A tip for an engineer student, the answer usually is in the documentation.

Thank you so much, sir. All these was really helpful.
I’ll keep the tip in mind.