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Brushless motor

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New Member
Dear All,

I need your help. I have one brushless motor with controller.
The motor have a 3 wire (3 phase) what is drived by square wave.
(not perfect square). I would like to sensing a direction of motor
by PIC microcontroller. If somebody have a idea, please write me.


Well-Known Member
Most Helpful Member
Don't you already know the direction of the motor since you are the one sending the control signal to the brushless motor controller?

But anyways, you can do it like this:

THe 3 windings of a brushless motor have to be commutated in a certain sequence. Google some brushless motor documents from Microchip or other PDF files to see what this sequence is.

You can then have the PIC tap into and measure the voltage on the 3 wires between the of the brushless motor and controller. Measure the combinations of which wire is at +V, which wire is at GND and which wire is floating. You will have to have some smart programming to decide which wire is floating and ignore it since it can be at GND or +V, or anything in between. You can take the speed of the how fast this sequence changes and what the sequence is to get motor speed and direction.
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