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DRV2667: Piezo Haptic Driver

Pratiksha Udgirkar
Prodigy 10 points
Part Number: DRV2667
Other Parts Discussed in Thread: DRV2700

Tool/software:

I have interface DRV2667 piezo haptic driver with PIC18F25Q10.

I am trying to generate some haptics waveform(Envelope Up , amplitude and frequency).
Till now I have tried one alert example given in datasheet and with that piezo is able to vibrate and give buzz sound.

I have attached the waveform for the reference.

Issues observed:-
1. I am always able to see constant amplitude of waveform irrespective of gain set in register.
2. The pattern of waveform I am trying to change by updating waveform register, but no changes in output waveform is observed.

Kindly help me to understand, if I am doing something wrong while updating values of header, control or data registers.



  • 0
    TI__Genius 9780 points

    Hello,

    Thanks for reaching out.

    Are you using the DRV2667 EVM? If not can you share your DRV2667 schematic? Also when sharing scope screenshots here is it possible to plot the differential output (OUT+ - OUT-)? 

    What is the capacitance of your piezo and what frequency are you driving?

    When you say waveform register, which specific register are you changing?

    Regards,
    Sydney Northcutt 

  • 0 in reply to Sydney Northcutt
    Prodigy 10 points

    Hello Sir,

    Thanks for the response.

    I am not using EVK board. The waveform frequency I have set is 195Hz.
    Please find attached doc for schematic, registers update and capacitance value.
    I don't have setup to see output voltage waveforms right now, after some time will update that.

    Thanks 1313h018v120.pdf,
    Pratiksha.

  • 0 in reply to Pratiksha Udgirkar
    TI__Genius 9780 points

    Hi Pratiksha,

    As the capacitance of the load increases the device is less capable of providing the full output range. The capacitance of your piezo load is quite large (850nF) so I believe this is the root cause here. One way to confirm this is to remove the load and observe the operation of the device. Below is a table from the DRV2667 datasheet that provides some test points for this behavior. I also included an image from the DRV2700 datasheet that shows this in graph form. 

    Regards,
    Sydney Northcutt