Gumstix Raspberry Pi CM4 + Pixhawk FMUv6

I can’t wait to see the possibilities for this new carrier board


It does look interesting!
At the moment it probably isn’t supported, unless the pinout coincides with an existing supported board.

Our senior engineer worked closely with the folks at Pixhawk to make sure that the CM4 + FMUv6 was designed to their gold standard. The pinout, connectors, and components were carefully selected to ensure that this board is a drop-in upgrade/replacement.

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Unfortunately that doesn’t mean a lot. This is the first “FMU v6” board, so it’s essentially untested and definitely not supported unless coincidentally. We recommend you engage with the ArduPilot dev team when developing new flight controllers - we have a lot of experience with the full spectrum of manufacturers, and in general would recommend against using the fmu vN reference designs. If you could send or post the pinout we can have a look.

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@Keith_Lee, Andrew will be sending test units to the PX4 Autopilot team for integration into our CI pipeline and to guarantee continuous PX4 support on the FMUv6 builds.

I recommend you send a few development boards to the Ardupilot maintainer team as well, they can help you set up your board and get it fully supported with ArduCopter, they are very knowledgable and helpful, I have no doubt they will provide assistance.

Perhaps @james_pattison can help you make the connections.

@rroche, I will discuss that with Andrew in about 15 minutes. Thank you and @james_pattison for the heads-up. I am hoping that we will be able to co-ordinate long term support for this and future Pixhawk-compliant boards produced here at Gumstix. We have added an FMUv6 building block to our Geppetto drag-and-drop PCB designer, so we’re hoping to see more of these designs out there.

I have heard back that there is already a discussion in place about providing Ardupilot developers with boards. :+1:

Yes - that discussion has been with me. There’ll be two boards coming at some point.

@Keith_Lee I’ve had a quick look at the schematic. You’re powering the servo rail from an onboard regulator and have the barometer/s on i2c??! Why?
I haven’t looked at dma mapping, timer allocation, or the add-ons like ftdi yet. How locked down is the design?

As per, pg7 the Bosch BMP388 pressure sensor is on I2C4.

The servo rail is actually powered by a current-limited distribution switch: TPS2041BDGN

I myself was not involved in part selection, but I’m sure this has something to do with the capacitive load of the servos and allows for over-current protection.

the distribution switch is going to be problematic: the servo’s shouldn’t be pulling board voltage at all, and there’s going to be strange behaviour when it cuts in and out. It might be fine for electronic speed controllers, but it won’t be for actual servos on the rail. I’m somewhat confused as to why it’s there. I assume the enable pin can be switched?
As for the baro: there really should be some justification for using I2C. It’s not a high speed sensor, but there are some nuances with those things and power on I2C: if it glitches on the bus it might not be able to be restarted.

I am unaware of any condition wherein a power glitch would occur that would prevent the sensor, or the bus, from restarting, but I’m very curious. What would the steps to reproduce this be?

This is really more of a concern with the v6 standard than with the CM4 + FMUv6 PCB, as all of the elements you describe above are documented in the spec.

What’s the status here? From Pixhawk FMUv6 it seems like the v6 standard itself is still a work-in-progress. Is the Gumstix board usable with ardupilot in its current state?

No, there’s been no work done to bring up ArduPilot on this board.

Curious if there have been any developments for getting ArduPilot for this board? Seems if not so far, there must be some deeper issues and no point looking forward for this board any time soon.

I’m waiting on an update re shipping. There should be boards on their way to @peterbarker and @ppoirier

Thanks @james_pattison , so it hasn’t completely grinded to a halt. Good to know!

Hello @james_pattison,

Could you please tell us if there has been any movement with this? It is a very interesting board and it would be great to know if it is an option.



Gumstix sent some out.
First pair:

Second pair:

They’re marketing/selling the device but haven’t addressed the heating issue. Patrick wasn’t comfortable continuing the port, and I didn’t push the issue.

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Thanks for the response. :slight_smile:

Wow, this is really disappointing! I think it is really promising to have this level of integration with a RPi CM4. Pity the Gumstix team is not more committed to this project (or at least that is how it seems).