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help to run dc brushless motor

Discussion in 'Sensors and Actuators' started by infidelboy, Mar 18, 2011.

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  1. infidelboy


    Aug 8, 2010
    i have bought a brushless motor from robokit and tried to run it with at80s52.. but i am not able to run it.

    here is image of motor i bought

    at the input power pin, i have applied a 12 V dc.
    at the other three pins i have applied the control pulse, but it is not working.

    here is the programing code for the control pins i used

    #include <regx51.h>
    sbit i1=P2^0; //for control pin 1
    sbit i2=P2^1; //for control pin 2
    sbit i3=P2^2; //for control pin 3
    void MSDelay(unsigned int);
    void main()
    { P2=0x00;


    void MSDelay(unsigned int a)
    unsigned int i,j;
    for (i=0;i<a;i++)
    for (j=0;j<1275;j++);

    resulting in output as...

    whats wrong here..
  2. infidelboy


    Aug 8, 2010
    /* with at89s52 microcontroller
  3. shrtrnd


    Jan 15, 2010
    Well, I guess my first question would be, what voltage does that 'brushless motor' operate at? Your IC operates at 5V. If your 'brushless motor' operates at a voltage/current higher than your input voltage/current to it, the motor won't spin.
    Are you wiring this thing in such a way as to expect the IC to supply drive voltage to the motor? I would expect this to be your problem, think about it.
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    OK, that motor requires up to 25A. Your uC can supply, perhaps, several tens of milliamps.

    You need either 1000 microcontrollers, a much lower current motor, or something that can switch 25A operating from the output of the uC.

    I think the last is perhaps the solution you're after.

    Switching 25A into an inductive load is not trivial.

    At the very least you'll require a logic level mosfet capable of switching 25A and a 25A diode to save it from the huge spike that occurs when it gets turned off.

    However it's possible you will not be able to find a logic level mosfet with good enough specs, and even if you do, the current required to switch it quickly will not be available from the uC output. This will mean very hot (and possibly failing) mosfets.

    You would be best advised to get some mosfet gate drivers to drive suitably rated mosfets (you may need a higher voltage rail for this too) and obviously some mosfets and the catch diodes.
  5. ranger306ci


    Apr 5, 2011
    simple solution

    are you using the included speed controller listed in that link? If so, I think you are wired incorrectly. The three wires from the motor go to the large 3 wires coming out from one end of the esc. the red and black on the other end are power. Rc typically use 2S or 3S Lipo's. You only need one pwm signal, and that goes to the signal wire on the servo connection. Now, if you are using that esc, to get it to arm it needs to see a low signal first.
    Last edited: Apr 6, 2011
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