Unknown RED HUD message

Hallo, I’m new here but a long time lurker.

I’m facing a strange problem with my home-built quad.

I have a pixracer board with arducopter.

I don’t know what I did, but after some tweaking I can’t arm anymore the motors and I continuously get a RED WARING message on the HUD: “NO changshenbo”.

Since I can’t find any reference to this anywhere, I decided to ask here fr support.

Does anyone have any suggestion?

Thank you


Could you please make a screen capture of it ? Also, what version of Mission Planner and firmware do you use ?


I’m using arducopter 3.4 and MP 1.3.72.

Here is the screen capture: https://ibb.co/gJ61tyR



do you have custom warning turn on? in warning manager?

Hallo Michael,

I don’t have any custom warning active:

EDIT: With mavlink inspector I’ve understood that the message is being sent from the flight controller.

I will try to replace the stock firmware with a generic updated one…

i have no idea what you have on the flight controller, but it is possible

I’ve updated the stock firmware with latest arducopter selected by Mission Planner and the message has gone.

I’ve understood that it was related to the Optical Flow sensor, enabled but not installed on my flight controller.

Cheap chinese pixracer sold on aliexpress…

Thanks for helping in this troubleshooting.


Could I ask a favor unrelated to your issue? Could you post a screen shot of the HW ID screen after connecting to that Flight Controller? There seems to be some PixRacer clones around with only one IMU and I’m curious if you have one. I’m just interested as this question came up recently.

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I’m not sure what this HWID means…


Thanks Dave for bring this to attention, I was thinking of getting a Pixracer from China - second thoughts now.

Need the whole screen like the following. This is a PixRacer with 2 IMU’s.