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Sensored lab 12b with Hall sensors

Armand M.G.
Prodigy 205 points

Other Parts Discussed in Thread: DRV8312

Hi everyone,

I am working with the DRV8312 kit and a tms28069. My aim is to have a sensored motor control, in my case with Hall sensors. Due to the fact that only a quadrature encoder is supported in the Instaspin labs (lab 12b), would it be possible to modify this lab to try to make it work with Hall sensors? Does it make any sense?

Thak you very much!

  • 0
    TI__Guru** 119680 points
    it doesn't make much sense, no.

    hall sensors don't give you precise enough rotor position estimation for position control. for velocity control they can be "good enough" for some applications but in those you really wouldn't benefit from trying to use the MOTION components with such a low resolution sensor input.

    our sensorless observer FAST actually is more accurate (above a minimum speed) than hall sensors. Hall sensors are good for zero speed and start-up though, so they do have their uses.
  • 0 in reply to ChrisClearman
    Prodigy 205 points
    Ok Chris, thank you for your answer.

    Regarding the encoder now, how can i find, in the code, the place where the GPIO ports (20, 21 and 23) are read??? I can not find it in any of the source files.

    Thank you
  • 0 in reply to Armand M.G.
    Intellectual 655 points
    Those are read via the quadrature pulse encoder (QEP) object, in qep.c/h. GPIO20..23 have alternate uses, which you can select via the GPIO MUX. These pins are not read via the GPIO registers.
  • 0 in reply to ChrisClearman
    TI__Guru** 119680 points
    BTW - there are hall sensored based FOC solutions. But to actually get close to matching sensorless observer angle tracking performance you need to actually create an angle observer for the hall sensors! This is effectively estimating an electrical angle between the hall states. There are several direct drive washing machines in production that use this technique to try to get FOC type performance on a very low cost simple MCU while still using hall sensors. I'm still partial to the fully sensorless direct drive washing machines using InstaSPIN-FOC :)