mma8452's g readings too accurate?

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mma8452's g readings too accurate?

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Contributor II

Hi, i have configured the device for high resolution and low noise. LNOISE bit is set, ODR is 1.56Hz, OS ratio: 1024. It's at 2g resolution.

I am getting steady results for x, y and z axis when the device is still.

The thing is i am always getting this: -0.026400g 0.012700g -0.967800g

So i am a bit confused because i was expecting some jitter (just like the one i am getting at ODR 200Hz).

Is this normal? I know the resolution is low (1024 count/g) but still.

thanks

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NXP TechSupport
NXP TechSupport

Hi,

 

What you are seen is normal in 1024 count/g resolution and ODR of 1.56Hz, with this combination you will practically not see any jitter, and I don’t think this is bad thing unless you need to measure vibration or very sudden movement, for such case I would rather recommend to increase the ODR frequency.  

 

Regards,

Jose

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274 Views
NXP TechSupport
NXP TechSupport

Hi,

 

What you are seen is normal in 1024 count/g resolution and ODR of 1.56Hz, with this combination you will practically not see any jitter, and I don’t think this is bad thing unless you need to measure vibration or very sudden movement, for such case I would rather recommend to increase the ODR frequency.  

 

Regards,

Jose

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Contributor II

Alright thanks for the heads up.

So do you have any recommendation from the NXP family of accellerometers for high accuracy low g

accelerometers with as high resolution and counts per g as possible. I would like to use it in a tilt sensing application for structures.

thanks

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NXP TechSupport
NXP TechSupport

Hi,

 

I recommend you the MMA8451Q, very similar to the MMA8452 you are currently using, but you can get a resolution up to 4096 counts/g.

There is an application note that I recommend you to read, the AN4075 “The Trade-off Between High Resolution and Low Power Using Oversampling Modes”, you can find it in the following link: https://www.nxp.com/docs/en/application-note/AN4075.pdf

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Contributor II

Thanks again.

 

I saw on some distributors that those chips are at the end of their life and i'd like to use something current.

Also, is 4096 counts/g the best you can offer? Is it enough for a tilt sensing application or do i have to use something more application specific?

 

Kind regards

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NXP TechSupport
NXP TechSupport

Hi,

 

The 4096 counts/g of the MMA8451 should be more than enough for tilt sensing application.

 

It is true that MMA8451, MMA8452 and other accelerometer families will turn into NRND soon since last order would be 12/1/2021 and last shipment would be 12/1/2023.

 

If you are looking an accelerometer for further future, I would recommend the FXLS8962.

FXLS8962 website: https://www.nxp.com/products/sensors/motion-sensors/3-axis/2g-4g-8g-16g-low-power-12-bit-digital-acc...

 

With the FXLS8962, you can geta  sensitivity of 1024 on +/-22g scale, which should be enough for tilt sensing application.