Arduino Servo Point Motor Control

Discussion in 'Other Electronic Interfaces' started by paul_l, Nov 19, 2016.

  1. redpiperbob

    redpiperbob Full Member

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    Hi All
    I was going to try a noise filter. but I had to give the select back. I will be able to get it back next weekend . So keep tuned
    be seeing you
    Bob
     
  2. redpiperbob

    redpiperbob Full Member

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    Hi All
    So I managed to hijack my friends Hornby Select again. I setup a noise filter system. and managed to get the following traces
    Yellow is the Select and Blue is my Digitrax Zephyr.
    Much smoother trace from the Select but I still cannot get any packet readings from the monitor pprogramme

    Has anyone managed to read any package information from Hornby's controllers?
    be seeing you
    Bob
     
  3. paul_l

    paul_l Staff Member Administrator

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    Hi Bob

    There still seems to a lot of interference and overshoot on the start of each change which may be making it difficult for the monitor program to pick up the start of the data block.
    Un-like the Digitrax which has nicely defined leading edges.

    Paul
     
  4. Colin_W

    Colin_W Full Member

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    I wonder if it's worth trying a small cap maybe a 0.001uF ceramic between pin 2 of the 6N137 and 0v to try and bleed off some of the high frequencies.
     
  5. Timbersurf

    Timbersurf

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    I know nothing, but I remember seeing this Mark Gurries thread with similar waveforms, not sure it is curable as Hornby is well know for it's poor NMRA standing and maybe its waveform too! Just a pointer, I will leave the black art of radio frequencies to those that know more than me! It also smacks of something else I read about schottky diodes being need, else silicon causes the ringing?
     
  6. redpiperbob

    redpiperbob Full Member

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    hi timbersurf
    I have looked into this a bit more and heard that Hornby played about with the standards to make the system backward compatible with the Zero system. I don't know if that is true but it would explain a lot.
    anyway I have tried all sorts of ways to read the packets and have totally failed. Including schottky.
    Sorry all If I do find an answer you will be the first to know.

    be seeing you
    Bob
     
  7. Colin_W

    Colin_W Full Member

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    Hi guys, I have been in the dred-shed again and have been using the servo driver that Paul built at the start of this thread but using the Arduino Pro-Mini boards instead.
    I originally used one pcb and passed the servo signals across the board junction on a 26 way cable. 26way.jpg

    Then I realised it only takes me an hour or so to build a board so I built a couple and put one on each side.

    PCB 1
    PCB 1.jpg
    PCB 2
    PCB 2.jpg
    The cross board connection is now only 6 wires and two spares.
    8way.jpg
    I will build two more PCBs for the next two base boards as all servo control signals are carried by the DCC twisted pair Green/White.
    Those of you with the eagle eyes will notice that only PCB 1 has the Lancaster MK1 Mosfet mod to delay the powering of the servos as in Paul's build. This is because the Black/White pair of wires will carry the delayed 5 volts for the servos across all the boards. Normal 5 volts will be carried by Red/Black pair to power the boards. There are now 8 servos running happily (so far) on the boards, 3 on PCB1 and 5 on PCB2. The dcc addresses are 501 which operates one servo on PCB1 and one servo on PCB2, 502 which operates the other two servos on PCB1, 503 which operates three servos on PCB2. 504 which operates the last servo on PCB2. Both PCBs have spare outputs.
    The dcc is controlled by the Lenz system at the moment.
    Layout.jpg
    Bed time
    Col
     
    Last edited: Aug 1, 2018
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  8. paul_l

    paul_l Staff Member Administrator

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    Looking good Col, sweet dreams
     
  9. Colin_W

    Colin_W Full Member

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    Belladrum festival from tomorrow, may be brain dead by Sunday and have to start all over again. By the way the Servo tuner worked like a dream, the main problems I had were mechanical and fingers. Just chilling with a practice beer now and watching Frankenstein on the TV. Now there's an idea :scratchchin: :avatar:
     
  10. paul_l

    paul_l Staff Member Administrator

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    [QUOTE="Just chilling with a practice beer now and watching Frankenstein on the TV. Now there's an idea :scratchchin: :avatar:[/QUOTE]

    Are you suggesting we connect Electrodes to Toto's ....... neck, may work for keeping awake at exhibitions :confused: :avatar:

    Paul
     
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