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newbi IUM problem
#1
sorry if this has been answered. I have searched hard for solutions.

I have been trying for several weeks to get IMU data into signalK (lockdown has provided the time needed!).  I have tried sigKsens, senseESP and now pypilot.  I can get other sensors to work fine, but not IMU.  I have 2 MPU5250 (blue from ebay) and a BerryIMU.  
I can read the data using a simple script on and Arduino.

Pypilot for dummies is great, but is a little unhelpful for users outside the USA where the recomended IMU from the store is not avaliable.

When pypilot is started, it does not detect any of th IMU's.  Have I missed something obvious?  Any advice is welcome.  Keeping this short, but can supply any info that might identify my failings.
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#2
Indeed the Invensense MPU9250 and the MPU9255 are obsolete. Some old batches can still be found on ebay, amazon or aliexpress.

Make sure you don't buy the bad apples as documented here. And make sure you buy some on reserve since some IMU's arrive DOA or do not perform according to spec (here). Or you could ask Sean if you can buy from him.

If you want a current IMU you could also try to buy a TDK/Invensense ICM20948, but support for that IMU has just arrived in github and it has not landed in TinyPilot or OpenPlotter yet (see the last post in the first link).

PS please make sure you type more accurately, since one a slight difference in the number is a world of difference in the IC.
PPS both the writer of the dummy manual and Sean are like me from Europe.
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#3
(2021-03-19, 12:53 AM)hreuver Wrote: Indeed the Invensense MPU9250 and the MPU9255 are obsolete. Some old batches can still be found on ebay, amazon or aliexpress.

Make sure you don't buy the bad apples as documented here. And make sure you buy some on reserve since some IMU's arrive DOA or do not perform according to spec (here). Or you could ask Sean if you can buy from him.

If you want a current IMU you could also try to buy a TDK/Invensense ICM20948, but support for that IMU has just arrived in github and it has not landed in TinyPilot or OpenPlotter yet (see the last post in the first link).

PS please make sure you type more accurately, since one a slight difference in the number is a world of difference in the IC.
PPS both the writer of the dummy manual and Sean are like me from Europe.

Hi there, 
Thanks for the reply, Yes, I did meant MPU9250.  
The MPU's I have are not DOA, they work with a simple Arduino sketch, and I can monitor the signals, they show the correct i2c address. However pypilot does not recognise them. 
With regard to the BerryIMU, there is a series of pdf's online documenting setting up pypilot with that IMU.  There is no detail on how this is configured.  Is this something that can be achieved easily?  
It is certainly a frustrating step in building a working system and have probably spent more on IMU's that the rest of the system combined.
Thanks again.
Cheers
Logan
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#4
Please do check the link on the "bad apples".
They should all be either MPU-9250 or MPU-9255 and they are all blue...
I think the IMU's with the print "MPU-92/65" have problems, while those with the print "MPU-9250/6500" and "MPU-9250/6500/9255" generally should work.

I also did have some purple ones working (MPU9250 + BMP280).

I would suggest to use i2cdetect to check the addresses ("i2cdetect -y 1"), but TinyPilot does not have i2cdetect installed.
OpenPlotter does have i2cdetect, if you have an RPI4 available...
( I tried i2cdetect and i2cdump on the TinyPilot as well. Perhaps an i2c-tools package should be made for the TC.)

Edit: another suggestion which might follow from above: use a raspbian armhf system to test some IMU which is not known to work. This also includes a standard OpenPlotter system with NOOBS on a RPI4.
(1) the armhf system is best supported for the Raspberry Pi.
(2) the Raspbian/Raspberry Pi OS is more complete than TinyPilot
(3) (but that should hardly be a problem with Raspberry Pi OS) use Buster or older. Using Ubuntu 20.04, Raspi OS Bullseye or newer and you might run into dependency problems for dropped packages.
With Ubuntu 18.04/arm64 I still had a working IMU using OpenPlotter packages, with Ubuntu 20.04/arm64 Qt4 was dropped...
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#5
had a look at the 'bad apples"....
and closed match numbers wise is the big red cross.
Have ordered a selection more from ebay including a purple style.

I2c detect has always worked and port is correct.

fingers crossed. thanks again.
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