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Power Sense Module Help

Hello, I’m part of a student team designing an AUV and we plan to use ArduSub. I have some questions regarding the Power Sense Module (PSM) and the PixHawk.

In the PixHawk’s documentation, it mentions the following regarding power:

If we are supposed to connect the PSM input directly to the battery, won’t the PixHawk receive voltage outside of it’s nominal range? If so, does that mean the PixHawk must powered using the servo rail input or USB?

I’m concerned because I just saw another post here saying they fried their PixHawk using the PSM.

Thanks!

Hi @one_au,

It depends on the PSM you are using. If you are referring to our PSM, it does not provide power to the Pixhawk, thus it must be powered by the servo rail or USB. Other power modules like the original 3DR and MRobotics ones do provide power to the Pixhawk, I believe at about 5.3 V.

Any posts you see referring to a power module killing a Pixhawk are due to older less reliable off the shelf power modules that used to ship with the BlueROV2, which is why we now make our own PSM. They could fail in a way which resulted in battery voltage being sent to the Pixhawk.

The existing version of the PSM is very reliable and we have not had any reports of issues, the way it is designed without sending power to the Pixhawk it cannot cause a failure like the old ones did.

-Adam

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Adam,

Thank you for the quick and detailed response!

A couple more things:

Since the power module input is the priority input for powering the Pixhawk, will it automatically detect that the voltage is too high and switch to using the servo rail for power?

Where is this servo rail input on the Pixhawk? Nothing on the documentation seems to label it.

Thanks!

Hi @one_au,

If you are referring to our PSM, as previously stated it does not provide power to the Pixhawk. There is no voltage coming back from the PSM other than the sense lines. There is no point at which “voltage is too high”. If there is high voltage coming in to a power line on the Pixhawk it will be damaged.

-Adam

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