I am going to connect a How to drive a linear resonant actuator to bela? Is there any tutorial for such an application? Do I need to add other drivers to the circuit? I assume that analog output of bela can directly drive the LRA.
How to drive a LRA by bela board?
I have never tried with a Liner Resonant Actuator but for Eccentric Rotating Mass motors (the little coin vibrators) you can use the analog output in conjunction with a MOSFET and diode like in the attached schematic.
The Diode is important as it provides a safe path for the inductive kickback of the motor that happens when it stops suddenly. The value of the resistor will impact the maximum speed of rotation you'll get from the motor. If you pull too much current from Bela the board will restart though so chose this value carefully.
6 days later
bela_robert It sounds cool. Do I have to use a motor driver?
I never used a LRA, but I just read a couple of articles about it. It seems like Bela could provide the basic functions to run it, when provided with a power transistor as per the schematics above. However, some more advanced functions, especially those that make use of feebdack loops, may only be achieved using a dedicated driver. This one seems promising: "The DRV2605 device [...] eliminates the requirement to design haptic waveforms because the software includes over 100 licensed effects and audio-to-vibe features".
If I were to use LRAs, I would probably start off trying to run them from Bela directly, but I understand it's pretty tricky to program haptic effects right (it's a science in itself). So, - if unsatisfied - I would then add something like the DRV2605 which has pre-cooked effects ready for use.