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Original question:

DRV2605: How to create custom waveforms

DRV2605L: Trying to drive LRA's with custom waveform

matthew liggett
Prodigy 10 points
Part Number: DRV2605L
Other Parts Discussed in Thread: DRV2605, DRV2604L

Tool/software: Arduino, DRV2605L breakout board (Adafruit), Apple Taptic Engine LRA

This part of the data-sheet suggests that it is possible to provide the DRV2605L waveforms that can be used to drive vibration actuators. I'm looking to implement a workflow where I design vibration waveforms using another software package and test/implement these through the DRV2605L to LRAs

If I'm interpreting the RTP function incorrectly, is the "audio-to-vibe" feature something that can accomplish what I want? I saw on another thread that the DRV2605 cannot store waveforms as it lacks the sufficent ROM. Is it possible to pass the waveform from another ROM source (for example an arduino or similar) through the DRV2605L? I have also seen somewhere that using a 1µF capacitor, I can pass the line input from an audio device to the In/Trig pin of the DRV2605L. Would this feature work with what I'm after?

Thanks in advance - Matt

  • 0
    TI__Genius 17820 points

    Hi Matt,

    You may be more interested in DRV2604L. DRV2605L and DRV2604L are very similar devices. The difference being that the device ending with a 5 has an integrated waveform library, but you can not alter the memory. The device ending with a 4 does not have the waveform library integrated but it has empty memory were you can store and play your own custom waveforms. Our GUI for the EVM (Haptic Control Console) has a RAM manager where you can build waveforms. 

    For RTP mode, you can only alter the amplitude to change the drive signal via I2C (in open loop mode you can also alter the driving frequency). If you used this to create some waveform it would likely be a lot of I2C transactions. For audio-to-vibe mode, an audio analog signal would be fed to the IN/TRIG pin. The specs for the IN/TRIG pin are from 10-250kHz, so I don't believe this is what you are looking for either. 

    Does DRV2604L sound better for your application? 

    Regards,
    Sydney Northcutt

  • 0 in reply to Sydney Northcutt
    Prodigy 10 points

    Hi Sydney. 

    The DRV2604L does look to be more in line with what we need. However, the hardware is outside our budget. We also already have DRV2605Ls on hand and would be pushing for time if we made an order for the 2604L. 

    At the moment, we're just concerned with finishing a prototype. The waveforms passed would be much less than a second. Assuming I2C transactions are not a concern, what would be involved in setting up RTP mode with timing and amplitude? 

  • 0 in reply to matthew liggett
    TI__Genius 17820 points

    Hi Matthew, 

    Ah I see. If you are in RTP mode and in open loop you can adjust both the amplitude and frequency. When these registers are altered via I2C they are immediately reflected on the output, so the I2C writes from the microcontroller would need to have the timings to create the waveform. The amplitude address is 0x02 and the output period (1/freq) address is 0x20.

    Regards,
    Sydney Northcutt