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I have BLDC motor. I just powered up the hall effect sensors by connecting 5 V to my STM32 dev board and also connected the ground pin. Then I checked the voltage on output pins while rotating the motor by hand. Each pin gives 0 V all the time.

What is the issue? How I can solve it?

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  • \$\begingroup\$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. \$\endgroup\$
    – Community Bot
    Commented Apr 12 at 20:56
  • \$\begingroup\$ How did you establish each pin give 0 V all the time? A multimeter will not be good enough here. \$\endgroup\$
    – greybeard
    Commented Apr 12 at 21:00
  • \$\begingroup\$ Is this the same three phase BLDC motor as in your other question Hall-effect sensor of a three-phase BLDC motor? \$\endgroup\$
    – Chester Gillon
    Commented Apr 12 at 23:32
  • \$\begingroup\$ why are you asking the same question again? \$\endgroup\$
    – jsotola
    Commented Apr 13 at 6:16
  • \$\begingroup\$ i just power up the hall effect sensor through stm32. i connected the power pin of hall effect with 5v stm32 pin and connect ground pins of both. and then i rotate the motor by hand to check is hall effect sensor working fine or not. i checked the voltage through multimeter of all three output pins of hall effect sensor. i am getting 0v all the time on each output pin while rotating the motor. i think voltage should be changed when i rotate the motor. am i correct? \$\endgroup\$
    – Sajid Ehsan
    Commented Apr 13 at 11:14

1 Answer 1

Reset to default
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You need a pull-up resistor on each of the hall outputs. They are open-collector.

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  • \$\begingroup\$ thank you. recommend me which value of resistor i have to use for pull up \$\endgroup\$
    – Sajid Ehsan
    Commented Apr 13 at 19:05
  • \$\begingroup\$ Around 5K is common. \$\endgroup\$
    – John Birckhead
    Commented Apr 15 at 12:10
  • \$\begingroup\$ thank you now its working. I powered up the Hall effect sensor with my controller and observed that my motor completes its six-step commutation in 90 degrees. To complete a 360-degree rotation, it takes 24 steps. How can I determine the number of poles through this observation? \$\endgroup\$
    – Sajid Ehsan
    Commented Apr 17 at 8:35
  • \$\begingroup\$ Choose one Hall device and rotate the motor. The magnets have alternating polarity , so each time the Hall device changes state, it is crossing the boundary to another magnet. You can count the magnets this way. The number of magnets equals the number of poles. \$\endgroup\$
    – John Birckhead
    Commented Apr 18 at 12:42
  • \$\begingroup\$ thank you. do you know how i can control speed of bldc motor through potential meter. i am using trapezoidal control algo \$\endgroup\$
    – Sajid Ehsan
    Commented Apr 18 at 14:12

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