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DRV-ACC16-EVM: G value calculation issue

Part Number: DRV-ACC16-EVM

Hi Team,

The customer is experiencing below issues and needs your help.

1. I want to confirm with you that the algorithm for this waveform is 49(Vpeak)/57=0.86gpeak,

Or 76(Vpeak to peak)/57/2=0.667gpeak.

 Which algorithm is correct?

Judging from the following waveform.

2.The product we tested is vibrated through Piezo. Piezo is connected to a board to drive.

We directly use the oscilloscope to measure the waveform of the drive board connected to Piezo, as shown in the figure on the left. It can be seen that the amplitude of the waveform is very large.

The waveform on the right is measured by TI DRV-ACC16-EVM accelerometer attached to the measurement point. However, there are some stacked structures on piezo, so the vibration of piezo will pass through these structures before the G value can be measured by the TI DRV-ACC16-EVM accelerometer. It can be seen that the amplitude becomes very small.

We want to know why there is such a big difference in amplitude.


3.We have the G value measured using different accelerometers(Data on the left) and the G value measured using DRV-ACC16-EVM(Data on the right).
But the G value measured by DRV-ACC16-EVM is much smaller. 

Both accelerometers use the same measurement technique. We put Accelerometers on the measuring point to measure the G value of piezo vibration. There are some structures stacked above the piezo.

Do you know the possible reason?



  • Hey Annie,

    I will take time to look into this and get back with you monday.

    Best Regards,


  • Hi Carson Allen, this is Wen.
    I am the questioner of this question. Is there any answer to the above question?

  • You are correct in the formula being Vpeak/57mV = G

    Could you explain again what that 2nd recording was again, is it the output waveform from a 2nd type of accelerometer? why is the voltage so large?

    Also from what axis are you measuring from on our EVM?



  • 2.The amplitude is so large that the waveform driving piezo is directly measured through an oscilloscope. We use the board to connect piezo and pull a wire out to connect to the oscilloscope.

    But we want to know why the gpeak measured by TI is so small. It is much smaller than other accelerometer measurements.

    Is there an answer to this question?



  • We only measure the Z axis.



  • The above Vpeak/57mV = G refers to Vpeak(max), am I right?

  • Yes that is correct

  • Yes Wen I agree this seems odds, are two charts part of the same measurement, it doesnt really seam like the acceleration is correlating at all with the signal out from the board.

    Could I possibly get a comparison of the DRV acceleration with one of the other accelerometers you are using for another comparison?

    It may be possible this is a faulty device but I am not sure yet.

    Best Regards,


  • Hi Carson, how would you compare they?
    The other accelerator information we use is as follows.

    The Accelerometer controller we use is 3560-C-T08 Pulse, and it uses the Model: 356A03 (supplier: PCB) sensor to sense.

    We measure the G value of the same measuring point just like the two tables seen in the question.

  • Hi Wen,

    If you are measuring consistently different with multiple other accelerometers, you may just want to consider this a faulty unit and maybe want to reach out for a return. There is not much I can really debug for a unit like this.

    Best Regards,


  • Hi Carson, we didn't want to return the goods, because the customers and manufacturers who work with us also use DRV-ACC16-EVM for measurement.We just want to know whether it is possible that the G value is different due to machine differences or signals.

    We need to understand this instrument to help us measure.

    1.If we input the waveform on the left side of the figure below, the waveform is all positive values.

    Then the input wave type of your user guide is a positive and negative wave type. Will this affect the calculation of G value? Does the formula need to be modified?

    2.Is it possible to provide the principle of this formula Vpeak(max)/57mV=gpeak?

    3.Does the tightness of 3M tape affect the measured value?
    I asked Evan of your team, and he said that it will affect the G value.
    Then I want to know how to define whether the 3M tape is tightly attached to the measuring point.

    If I use tape to strengthen the stability, will it also affect the G value?

    Sorry I have a lot of questions, because TI DRV-ACC16-EVM will be used in the project, so I hope you can help answer these and previous questions.

  • The user guide uses the formula Vpeak-peak/57/2=gpeak. Is it because of DC coupling?



  • Hi Wen,

    Actually before I investigate any further is the object that is vibrating isolated from the rest of the environment by some type of phone or cushion? feel free to send pic of overall test set-up.