MPU 9255 inverted Accel readings

Other Hardware Robotics
1

Hi,

I’m using GY-9255 and Arduino nano boards but I don’t have idea why I have inverted raw values for all Accel axis.

Please, anybody have similar experience?

Thanks

2

but I don't have idea why I have inverted raw values for all Accel axis.

Maybe you mounted it the wrong way.
Who knows?

3

Thanks AWOL, I checked it and really the values are inverted. I have positive gravity reading (raw values with any math operation) on all axis when they are pointing up.

Note that I’m having correct readings for the AK8963 and it is access directly on I2C bus. Master I2C serial interface on MPU9255 disabled.

I will check if the gyro readings are inverted too when I back from Holliday.

Thanks and Merry Christmas!

4

That is the correct result.

The sensor measures the difference between the forces on the sensing element, which you can think of as a mass hanging from a spring, and those acting on the sensor frame (the IC). The sensor does not report the acceleration due to the Earth's gravity, which acts on everything, rather it reports the upward acceleration applied by your workbench, which keeps the device from falling.

Likewise, when you accelerate the device by pushing on it in the +X direction, that will be a positive acceleration along X.

Accelerometers register zero acceleration on all axes when in free fall.

5

Thanks, jremington. I understood your explanation. I will check it when I back.

Many thanks and Merry Christmas!