DRV2605 LRA LIbrary duration and intensity

Hi, George:

a) we don't have the table showing the durations of the waveforms.
b)we can adjust the "Sustain Time Offset".
c) once the rated voltage is fixed, we cannot change the predefined voltage/time pairs.

Thanks.

Hello,

thanks for your fast response.
a) Thanks, I will try to experimentally measure.
b) Does the STO work also for the LRA patterns? From the datasheet I had a feeling it would be only working for ERMs. Can you please confirm?
c) Thank you. It is clear.

Best,
George

Hi, George:

b) it works both for the LRA patterns and ERM patterns.

Thank you for your answers. I tried it out and seems that it works only for certain LRA patterns but not for all. For example using the SPT I was able to increase the duration of any of the Soft Bumps but none of the strong clicks. Is there any explanation for it?

Thank you in advance, 

George

Hi, George:

"Any positive voltage value other than the overdrive portion is considered as a sustain positive value."

i am not sure. my guess is that that waveform data doesn't contain the "sustain" portion.

Thanks.

George,

I am going to investigate the STO to see if I could shed some light on this. Would you be able to provide me the following:

• Model # of the Actuator being used?
• Open or Closed Loop?
• Register settings

• For your default comparison
• When obtaining increased duration in the waveform

Thanks,

Javier Palomo

Hello Javier, 

and thank you for your reply and willingness to help. Here the answers below:

• Model # of the Actuator being used? C08-001 Precision microdrives LRA
• Open or Closed Loop? Closed Loop and LRA mode
• Register settings SPT register set to +127 (01111111). Assuming the default PLAYBACK time 5ms -> Total expected duration extension 127 * 5ms -> 635ms (easy to be noticed)

•  Using the value above play any of the effects #1-6 , 10, 12-40, 44-57,64-69: No noticeable different in duration. Now, Using the same value play any of the effects #7-9 , 11, 41-43, 58-63, 70-117: Noticeable different in duration. 
• My high level code structure, first performs an autocalibration to the motor, sets all registers to default values apart from SPT, goes in LRA closed loop mode and drives the LRA with a stored effect from the library.

Let me know if you need anything else,

George 

George,

Of course, and thank you for that information. I should be good with the information provided and as a disclaimer I couldn't find one of the C08-001 LRA's in the lab, but I will be testing it on another LRA with the same 235 Hz resonant frequency.

Best Regards,

Javier Palomo

George,

After doing some analysis, I too was able to expand/shrink some waveforms using SPT/SNT, and others I was unsuccessful.

Here is what I tested setting the Sustain Positive Time register to 0x04 (therefore a 20mS offset). As seen in figure 1 we used a waveform generator to simulate what waveforms 1(strong click) and 7(soft bump) would look like with and without a SPT delay.

As you can see both (Simulation, and scope measurement) the generated waveforms for Waverform7 had approximately a 20mS increase in the length of the sustain portion of the wave form (Figure 1 & 2).

Then, when looking at Waveform1 you notice there is no change on both simulation and scope measurements on Figure 3 & 4 (consistent with your findings).

 

Figure 1

 

Figure 2

 

Figure 3

 

Figure 4

 

Figure 5

 

What it comes down to is pretty much what Peter Li mentioned in his above response. Since there is little or no sustain portion in the waveform for the Strong Click, the SPT/SNT cannot increase nor decrease the non-existent portion of the wave. You can increase both the ODT and BRT since those sections of the wave are within the wave form (I am not recommending increasing the ODT/BRT for it can damage the actuator by over driving, just proving a point).

I did not go through all of the waveforms as you did, but from what I noticed the waveforms that the SPT/SNT did not change was due to the little or no sustain portion of the waveform.

Is there a particular reason as to why you wanted to expand or shrink the waveforms for your application?

Best Regards,

Javier Palomo

Hello Javier, 

and thank you very much for your response and the provided experimental data, which clarify the situation. 

No particular reason. I wanted to investigate the duration of the pattern as an input parameter. 

Thank you, 

George

George, 

Not a problem, let me know if there are any other questions that you may have!

Best Regards,

Javier Palomo