IMU Confusion

I’m still working on my first PCBv2. The parts list has the MMA but I’ve now been reading that it won’t work on my PCB and that I need to use one of the Bno chips… is that right? If so which Bno should I try to get? There seems to be a few different ones floating around and I’m at a loss…

It appears difficult to get one these days. Unless you’ve got a decent slope on your land, try without an IMU or use dual GPS.

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The main thing needs to be started in order to work without the IMU. IMU is already a supplement to improve performance.

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There are already 3 different IMU that work with V5
Bno08x, cmps14, and witmotion 901. Search for the words (with magnifying glass at upper right) to get more information.

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There appears to be a global shortage of BNO085s and my guess is that’s because the Chinese car industry needs them. Could be wrong, but I can’t think of many other reasons for this.

I’ve just managed to squeeze in an order with a Chinese supplier, but they really are getting quite tricky to find at present.

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I didn’t really think it would work without it. I’ll give it a shot. We’re pretty flat here, there’s only a few spots where it might need it then.

@Larsvest thanks! I did search quite a bit but I saw so many different posts about each one that I didn’t find anything definitive about which to go with. I realize at this point that there are shortages though.

So far I have hardly used an IMU on our land, so little that I don’t know if it’s even doing anything useful. I have heard that the IMU helps with U-Turns though, and then obviously with slopes.

When planting /seeding this field, I did not have IMU activated. The uneven (snaky) lines are due to the front roller, which sometimes drag left then right.
It is a 4m set and the split is almost in center of picture.
F9p and rtk :slightly_smiling_face:


Do you know if these are as accurate / reliable as the BNO08x?

CMPS14 is the same chip as BNO08x, but it’s always using the magnetometer, which makes it bit more sensitive as regards placement in the cab.


Any idea why bno08x zeroes when restarted and if I’m not facing north with the tractor I get a real big difference between gps and imu heading ? Is my bno defective? Sourced from aliexpress.

The IMU never faces north unless you are pointed at it. It only uses the heading variation, so it doesn’t matter if it points north, and if when you reset it, it has to come out 0.