Linux/DRV2624: Linux/DRV2624

Hello,

If you turn off the "AUTO_BRK_INTO_STBY" bit, then there will be no braking when the GO bit returns to 0. When the GO bit returns to 0, the part will go straight into standby mode. However, there will be braking if the RTP_Input is set negative or to 0 during operation.

Hi Kelly

      TKS for your reply.

      And I have another question about the auto-calibration.

     From the section of 8.6.7 of DRV2624 datasheet, I know that there are three important parameters that need to be configurated:  Rated Voltage,Overdrive Voltage-Clamp and Drive-Time.

     For Rated Voltage,Overdrive Voltage-Clamp, I really don‘’t know what are appropriate values, even if I get the computational formula of these two values from section  8.6.2.1 and 8.6.2.2.

    So could you show how I get the appropriate value of those two parameters? Then by these values  I can set a good value in register OD_CLAMP and RATED_VOLTAGE.

Ps: In the commom driver code of drv2624, RATED_VOLTAGE is set 0x53 and OD_CLAMP is set to 0x9b

Expect your reply

Best Regards

Shawn Wu

Hi Shawn,

You can use this tool to figure out the appropriate values. The Rated Voltage (RV) will depend on the LRA datasheet. This value is specified in V_RMS and our device setting is also in V_RMS. The Overdrive (OD) Clamp is specified in V_Peak, so make sure to set the OD Clamp voltage above the RV. We typically set the OD Clamp 1.25 or 1.5 times the RV. The Drive Time is defined in the datasheet; drive_time = 0.5*LRA Period.

Example: Datasheet RV = 1.2V_RMS and 200Hz

Set RV = 0x31 and OD Clamp > 0x53 (1.7Vp). Drive Time = 2.5ms

The OD Clamp can be higher to decrease the rise/fall times of the acceleration, but you need to check with the LRA manufacturer to make sure the LRA can handle the higher voltage.

Hi Kelly

      TKS for your prompt reply. It is very useful for me. And those questions:

       What is the  voltage range which can be output from IC, I dont find it in datasheet ?

       Can I turn off the "AUTO_BRK_INTO_STBY" bit before do auto-calibration ?

       It seems there is a tool that can tranfer audio rings to waveform data. Could you provide it?

      

Hi Shawn,

The output voltage is dependent on the VDD supply voltage. If you are using the EVM (5V), then you can achieve a max voltage ~4.6V using 0xFF for the rated voltage. At VDD = 5.5V, you can achieve ~5.1V output.
There is no braking after the auto-calibration. No need to change this setting.
I am not sure about this tool. In the previous device, DRV2605, we have an audio-to-vibe mode that accepts an analog input.

Hi Kelly

      Sorry, I'm not very clearly

      Does the output voltage also depend on the supply VDD?

      For example, when VDD is 4V or 3V , and the value of rated voltage reg is same,  does it  output  same vol?

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What's more, I want to double confirm about the original question

There is braking  effect when I set INPUT_reg to 0 and keep GO bit in Go under the premise that auto_brk_into_stby is 0 closed.

Is it right ?

TKS

Hey Shawn,

The maximum output voltage depends on the supply voltage, and the rated voltage is a fixed value that will not change if there is enough supply voltage. If the rated voltage is 3V, then the output will be the same if VDD is 4V or 5V or 5.5V. The supply voltage must be higher than the rated voltage, because the supply voltage sets the upper limit.

What do you mean by "that auto_brk_into_stby is 0 closed"?

Hi Brouwer

      From section 8.6.9.4.1.1, that we need 50ms to finish the auto-brake.   If there is trigger CMDs in this 50ms, it will be delay response or ingnore.

      For example if there 50ms,  it recivers a START trigger and then a STOP trigger, the STOP will be ingnore.

      It not the result we want since those CMDs are from user space.

So I need a way that can control the braking time,  not a fixed value.  That means the braking process can be broken off by control.

That is why I want to set AUTO_BRK_INTO_STBY to 0 (without auto brake). In stead,   trigger a braking effect by setting the RTP_INPUT to 0  in operation.   

About this ideal, please help to confirm