IC/circuit to shuffle 3 wires?

Discussion in 'Digital Circuit Design' started by Simas Chomentauskas, Nov 3, 2017.

  1. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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    Hi, I hope the question is not too silly :] I spent my fair time trying to google it out, thought I did it, got the part and then realized it's not going to do the job :]

    What I need is a method to shuffle 3 wires with MCU signal (hall sensors signals coming from hub wheel to controller board). That would enable me to control it's rotation direction.

    Let's say we have ABC->ABC connection, it then rotates CC. I need to be able to shuffle them and get ABC->BCA connected. It works if I do it manually. I thought I can do it with 1to2 demux IC, but they keep „unsused“ output HIGH, which is not ok for my application.
     
  2. simozz

    Member

    Jul 23, 2017
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  3. LesJones

    Well-Known Member

    Jan 8, 2017
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    If I understand what you are trying to do I thing two x two inpur MUXs should work. In your second sentance you say "I need to be able to shuffle them and get ABC->BCA" That is not reversing the sequence. It is just moving one step forward. If we put in several revolutions worth you will see it is not changing the sequence.

    ABCABCABCABCABC
    / / / / / / / / / /
    BCABCABCABCA

    You need to swap A with C. So the sequence becomes BCA. We will call the output signals X, Y, Z. B would be connected directly to Y.
    X would connect to A via one MUX for forward and to C for reverse.
    Z would connect to C via the other MUX for forward and to A for reverse.

    Les.
     
  4. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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    Should we call outputs XYZ, B is only connected to Y in forward. In reverse it's connected (getting 1-0 data) from A input.

    I guess basically what I need is 3 pairs of electronically controlled spdt switches.
     
  5. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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  6. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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    Nope, I need it to work with 5V supply and 3.3 logic control...
     
  7. dendad

    Well-Known Member

    Feb 20, 2016
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    I don't understand why you need to switch the signals. The Hall sensors are there to tell you the position of the rotor so the MCU can switch the currents to the motor to control the speed and direction. You don't need to change the hall sensor connections o change the direction.he MCU should do that for you.
    Are you trying to retrofit a directional control on a single direction motor?
    If so, you could just use one of these..
    https://au.mouser.com/ProductDetail/E-Switch/1004P1T1B1M1QEH/?qs=sGAEpiMZZMtFyPk3yBMYYA73A%2bONq4WtEQwy0Lf6YtE=
    3 poles for the Hall sensors and one for an indicator LED to show it is in reverse.
     
    Last edited: Nov 3, 2017
  8. WBahn

    Moderator

    Mar 31, 2012
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    If you have access to the MCU code, then do it in software. I'll assume that's not an option.

    Assuming that denddad's suggestion isn't applicable, one thing to keep in mind is that you don't need to switch all three signals -- swap any two of them and you've reversed the direction.

    Let's say you have ABCABCABC.

    Now, swap A and B and you have

    BACBACBAC

    Are these signals digital? It sounds like it from the solutions you have been trying (unless you are using analog MUXes?)

    Assuming they are digital, then two 2-input MUXes and an inverter should do it.
     
  9. LesJones

    Well-Known Member

    Jan 8, 2017
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    If you can give some more details of what you are trying to do we should be able to see why none of the suggestions so far meet your needs. We all seem to be assuming that you are trying to reverse a brushless DC motor. Why is the software solution not acceptable ? Why in post #4 do you say that you need "3 pairs of electronically controlled spdt switches" ? Swapping all 3 signals WILL NOT REVERSE the direction.
    Posting a schematic would be a great help.

    Les.
     
  10. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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    Got the point, WBahn. Though I think this wouldn't work, since it would offset all the signals from halls in relationship to the main phases signals.Your example also gives BAC, and what I need is BCA.

    Doing it in software isn't possible since I'm using a hardware controller (MCU only controls speed via pwm). It has a reverse function, but it's not working correctly. I accidentally found out that by physically swaping hall wires I can reverse it's motion, so that's what I'm trying to do - kind of fool it around.

    Here we go:
    [​IMG]
     
  11. LesJones

    Well-Known Member

    Jan 8, 2017
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    What I suggested in post #3 and what WBahn suggested in post #8 should work. I suggested swapping over A and C and WBahn suggested swapping A and B (Swapping B an C would also work.) Think of it just like reversing a three phase induction motor. A single CD4053 IC would probably work. You need to specify the signal levels of thedirection control signal and the signals that you are swapping over. You also need to specify the input resistance of the device that the hall signals are driving. We could then give you a better idea of a suitable multiplexor IC.

    Les.
     
  12. Simas Chomentauskas

    Thread Starter New Member

    Nov 3, 2017
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    Bingo - CD4053 looks like exactly what I need! Hall signals are +5, control +3.3, so according to datasheet it should do the job perefectly. Thanks, will let you know the result!
     
  13. crutschow

    Expert

    Mar 14, 2008
    19,528
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    That's still an ABC sequence.
    You need to swap A and B (or B and C) so the sequence is CBA.
     
    Last edited: Nov 4, 2017
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