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8051 microcontroller

Discussion in '8051/8951' started by dineshmudaliar, Jan 24, 2009.

  1. BeeBop

    BeeBop Active Member

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    Well, which cct did you use. Can you post or link to the schematic. Did you have diodes across the motor?
     
  2. siva_elven

    siva_elven New Member

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    Actually, there were no diodes in it, i only had in my mind to give a fixed voltage supply to both the microcontoller and the motor used, and it had no diodes.
    I had directly connected the motor to the microcontroller. pls help...
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You can't connect a motor directly to a microcontroller, particularly an 8051 which has very little current capability.

    You need an H-bridge, and the size of it depends on the requirements of the motor.
     
  4. dave

    Dave New Member

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  5. siva_elven

    siva_elven New Member

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    Well i found a circuit rite now, it connects to the microcontroller via a L298 operating at 5 volts, i think it would suffice.
    A L298 can be used instead of a h-bridge circuit, i hope so...
     
  6. BeeBop

    BeeBop Active Member

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    No, that will just provide drive current.
    Did you actually look at any of those links I took the time to find for you?
     
  7. siva_elven

    siva_elven New Member

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    Of course i did, and this is one of the circuits i got from there, i communicated there too, nd they sent me this ckt.
     

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  8. BeeBop

    BeeBop Active Member

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    Sorry! I read that as UNL2803 for some reason. :eek: Admittedly, I read hastily.

    Yes, the L298 is designed for that. There is a circuit diagram on page 6 of the ST data sheet. It shows a motor connected using fast recovery diodes for protection.

    The circuit you posted should work, but I would add the diodes. :)

    Get the data sheet for yourself, and give it a go. Come back when you have it hooked up, or ...

    EDIT: Just so it doesn't confuse you, the L298 is a dual h-bridge, and they are using the other one in each diagram.
     

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    Last edited: Feb 4, 2009
  9. siva_elven

    siva_elven New Member

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    can i use a 89S52 in place of the 8051, nd use the same program as well, bcoz i read that 8952 is only an advanced version of 8051.
    Pls suggest.
     
  10. siva_elven

    siva_elven New Member

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    can i drive the 12 Volt,1A DC motor, using L298, can i get the L298 to give me an output of 12Volts
     
  11. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Download the datasheet and read the specs - but basically it's not a very powerful IC.

    The motor current also won't be 1A, it will vary wildly, and during stall or heavy loads will be greatly higher than that.
     
  12. siva_elven

    siva_elven New Member

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    well, i indeed think of connecting the diods between the L298 and the motor, but i dont know which diode, and how to connect it, pls, relate it to the circuit above and send a suitable connecton between the motor and the diode. nd pls suggest which diode to use.
     
  13. siva_elven

    siva_elven New Member

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    can i use the Fast Recovery Diode, FR-301??? nd pls suggest the ckt diagram also.
     
  14. BeeBop

    BeeBop Active Member

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    Should work well. For a diagram, look at the picture I posted from the data sheet. (You DID get yourself a data sheet, didn't you? :D)
     
  15. siva_elven

    siva_elven New Member

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    i did download a datasheet of the ST electronics, but, i dont know whch ne, i looked it up, and i've got this diagram, just see it nd tell me whether this is the diagram or not.
     

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  16. BeeBop

    BeeBop Active Member

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    Looks like that is the correct data sheet, but that diagram is for stepper motors. It is on page 8, the one you want is on page 6. Look for the same diagram I posted... It is the same thing as what is shown in the circuit you posted, but with the diodes.
     
  17. siva_elven

    siva_elven New Member

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    yeah thnx, i got it, m on the ckt now...
     
  18. Ubergeek63

    Ubergeek63 Well-Known Member

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    Actually schottkys should be used. The fast diode's 1.2V drop, if he is driving the rated current, is actually quite lossy and if the drop in the chip is lower helps very little if it is a synchronous rectifying chip.

    Dan
     
  19. siva_elven

    siva_elven New Member

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    yeah tyhnx, i already noticed that, i went through the datasheet...
    thnx...
     

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