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DRV2605L to LRA open loop and setting resonant frequency
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DRV2605L to LRA open loop and setting resonant frequency

by dustyntobin on Thu May 19, 2022 11:31 am

Hello,

I am trying to set the DRV2605L to LRA open loop and set the resonant frequency for an LRA with a resonant frequency outside of the auto calibrate range. Per pg. 14 of the datasheet:
" For the LRA, the DRV2605 device automatically tracks the resonance frequency unless the LRA_OPEN_LOOP
bit in register 0x1D is set."

It's not clear how to set the bit as 0x1D also contains other functions such as ERM_OPEN_LOOP, SUPPLY_COMP_DIS, etc. The programming section on pg. 26 of the datasheet advises:
"To configure the DRV2605 device in LRA open-loop operation, the LRA must be selected by writing the
N_ERM_LRA bit to 1 in register 0x1A, and the LRA_OPEN_LOOP bit to 1 in register 0x1D."

What code would write the N-ERM_LRA bit to 0 and the LRA_OPEN_LOOP bit to 1?

Trying to understand and get a solution from from similar code, I found this in the audio example sketch:
Code: Select all | TOGGLE FULL SIZE
  // ac coupled input, puts in 0.9V bias
  drv.writeRegister8(DRV2605_REG_CONTROL1, 0x20); 
 
  // analog input
  drv.writeRegister8(DRV2605_REG_CONTROL3, 0xA3); 


But I'm hung up on where to go from here and how 0xA3 selects analog input. What value would I need to write to REG_CONTROL3 to use LRA open loop mode, or if I'm completely off base, how would I put the DRV2605L in LRA open loop mode? I'm hoping to reverse engineer the answer to this question to figure out how to set the resonant frequency.

Thank you.

dustyntobin
 
Posts: 2
Joined: Thu May 19, 2022 10:55 am

Re: DRV2605L to LRA open loop and setting resonant frequency

by dustyntobin on Thu May 19, 2022 3:20 pm

Solved. Some more study of how registers operate and instructions are read led to an answer.

dustyntobin
 
Posts: 2
Joined: Thu May 19, 2022 10:55 am

Please be positive and constructive with your questions and comments.