DCC++ track power

sachsr1 Jul 13, 2016

  1. sachsr1

    sachsr1 TrainBoard Member

    60
    23
    5
    I'm trying to set up my first DCC++ base station with JMRI, and I'm having a problem. I'm using an Arduino Clone, and a Deek-Robot motor shield. I can get the track power LED's to turn on, but I can't get power to the track. I'm using a 12v power supply, and used a multi-meter to verify that I have 12v to the power inputs. When the track power is on I have .22 volts on both the programming track and the main. I have 5 connected to 13 and 10 connected to 12. I have used the Uno for other sketches and it works fine. I have tried it with both DCC++ Controller and JMRI. I bought two motor shields and they both have the same result. Thoughts?????


    I get the following errors when compiling

    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:427:152: warning: backslash and newline separated by space [enabled by default]
    R.currentBit=0; /* reset current bit pointer and determine which Register and Packet to process next--- */ \
    ^
    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:433:100: warning: backslash and newline separated by space [enabled by default]
    R.tempPacket=R.currentReg->activePacket; /* flip active and update Packets */ \
    ^
    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:449:103: warning: backslash and newline separated by space [enabled by default]
    } /* END-ELSE */ \
    ^
    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:450:88: warning: backslash and newline separated by space [enabled by default]
    \
    ^
    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:196:59: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
    CurrentMonitor mainMonitor(CURRENT_MONITOR_PIN_MAIN,"<p2>"); // create monitor for current on Main Track
    ^
    /Users/r/Documents/Arduino/libraries/DCCpp_Uno/DCCpp_Uno.ino:197:59: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
    CurrentMonitor progMonitor(CURRENT_MONITOR_PIN_PROG,"<p3>"); // create monitor for current on Program Track



    UNO:
    https://www.amazon.com/gp/product/B00P2FX9WY/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
    Motor Shield:
    http://www.ebay.com/itm/310787745501?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT
     
    Last edited: Jul 13, 2016
    Scott Eric Catalano likes this.
  2. Atani

    Atani TrainBoard Member

    1,460
    1,697
    36
    for the motor shield, did you connect the 12vdc to the inputs on it and cut the VIN and BRAKE traces on the back?
     
    Scott Eric Catalano likes this.
  3. sachsr1

    sachsr1 TrainBoard Member

    60
    23
    5
    The 12vdc is connected to the motor shield input, and I cut the VIN, but not the BRAKE traces.
     
    Scott Eric Catalano likes this.
  4. Atani

    Atani TrainBoard Member

    1,460
    1,697
    36
    Scott Eric Catalano likes this.
  5. sachsr1

    sachsr1 TrainBoard Member

    60
    23
    5
    I never thought to test it with AC. JMRI was able to read the decoder, but I wasn't able to get it to run. I measured the track voltage and it was 10.8 AC, is that too low to run a HO train? I'll try it tomorrow with an 18 volt pack. I wanted to start with lower voltage in case I messed up.
     
    Scott Eric Catalano likes this.
  6. sachsr1

    sachsr1 TrainBoard Member

    60
    23
    5
    I switched to the 18v supply and I got it working.
     
    Scott Eric Catalano and Atani like this.
  7. Scott Eric Catalano

    Scott Eric Catalano TrainBoard Member

    205
    57
    6
    Hello,

    If you are using HO Scale locomotives you will need a higher power supply. I use a Pololu motor shield, which is rated for higher voltages, and a commercial power supply that I got with my digitrax DCC system which is also rated for use with N, HO, G scale and has a voltage selector on it with an onboard voltage meter so I know how much voltage is being supplied at any given time.
     
  8. BSR_SteveP

    BSR_SteveP TrainBoard Member

    14
    19
    3
    Bumping on this...

    First time setting up DCC and decided to use DCC++. (For the low cost alternative). So an Elegoo Mega board with the Pololu motor shield. Serial comms from the computer to the "BaseStation" seem good. Just no communication to the decoder. I too thought it might be a voltage issue. but Im hesitant in going with a higher voltage since in big bold letters in the Digitrax manual it says no higher than 16volts. Well, its DCC, You cant measure track voltage in DC with a simple multimeter. and alas I dont have an oscilliscope.

    TX/RX lights flicker with commands.
    voltage from the Mega does not power up the Pololu. so no cross voltage issues.
    power to Pololu makes a nice blue light with power supplied.
    Arduino IDE serial monitor <1> does turn on the red/green lights on both outputs, and <0> turns them off.
    JMRI power button does the same thing.
    AC Voltage at the track was measured to be 24Vs (?) when powered on, 0 when off.
    3 different decoders. DigiTrax - 2 of the 126 decoders and 1 166 decoder.
    JMRI will not read CVs. Says "308 - No acknowledge from locomotive" when trying to identify.

    Any suggestions?
    Thank you.

    Steve
     
    Scott Eric Catalano likes this.
  9. BSR_SteveP

    BSR_SteveP TrainBoard Member

    14
    19
    3
    RCMan helped me out tremendously. Case closed.

    Sent from my SM-N950U using Tapatalk
     
    Scott Eric Catalano likes this.
  10. Roger McCarty

    Roger McCarty TrainBoard Member

    31
    4
    7
    A DCC system outputs a constant voltage of about 14.5V AC. Be sure to use AC voltage measurement mode of your multimeter and ~not~ DC mode.
     
    Scott Eric Catalano likes this.
  11. Trusty

    Trusty TrainBoard Member

    52
    33
    6
  12. Roger McCarty

    Roger McCarty TrainBoard Member

    31
    4
    7
    If you examine the voltage on an oscilloscope you will see a modulated 14.5VAC waveform.
     
  13. MrChuck

    MrChuck TrainBoard Member

    27
    6
    2
    Bumping on this again...sorry I'm new and only got my DCC++ gadget four days ago.
    Cutting the BRAKE track on the motor shield isn't mentioned in the how-to videos from youtube. Is this something that has come to light since then?

    I have a followup question as well--what happens if you DON'T cut the brake track? Recommended doesn't equal mandatory, so if I don't care about the extra pins (which I don't), will DCC++ still work correctly?

    I have genuine UNO and motor shield, no clones here!
     
    Last edited: Sep 5, 2019
  14. Atani

    Atani TrainBoard Member

    1,460
    1,697
    36
    The youtube videos are very old and are not guaranteed to match up with the current code available on GitHub.

    By not cutting the brake pin trace, if the pin transitions to a HIGH state for any reason the h-bridge will cut all track output. The recommendation to cut the trace is not really tied to only freeing up the pin. It ensures that the track output is not unintentionally cut off by an unintended change in the pin state.
     
  15. MrChuck

    MrChuck TrainBoard Member

    27
    6
    2
    I'm glad I asked! Thanks for the heads-up, I'll do it today.

    But on reflection, I think I asked the wrong question. Where are the most up-to-date instructions for setting up the Arduino and motor shield? There may be other things I need to know about because I only looked at the old YT vids.

    Thank you,
    Charles
     
    Last edited: Sep 6, 2019
  16. Atani

    Atani TrainBoard Member

    1,460
    1,697
    36
  17. MrChuck

    MrChuck TrainBoard Member

    27
    6
    2
    OK, so that covers cutting the BRAKE traces. I've already cut Vin Connect on the Uno in line with the old instructions. Since it hasn't exploded and seems to be working OK, I gather this now doesn't have to be done on the shield as well?
    Otherwise looks like I'm good to go when my decoders turn up!
     
  18. MrChuck

    MrChuck TrainBoard Member

    27
    6
    2
    If I might make a suggestion--if this board supports pinning threads, might it not be worthwhile to gather the most up to date instructions and pin them as a resource for noobs such as myself? If there are forks going on, this is news to me and I don't know where they are or why. There are now over 3000 messages to sift through to find this information. Since Gregg isn't active at the moment--which was also news to me, but I noticed it in a random message I looked at yesterday, so it might be the case--I don't want to break something or run across avoidable problems, by using out of date instructions.
    Thanks!
    Charles
     
  19. Atani

    Atani TrainBoard Member

    1,460
    1,697
    36
    VIN should also be cut. This prevents feeding the DCC supply to the Arduino side, if you are using over 12VDC it can cause the voltage regulator on the Arduino to fail (check the docs for the specific Arduino board for it's limits). It is generally safer to cut the trace and supply independent voltages.

    Gregg has not been active for quite some time unfortunately. His version of the DCC++ project is virtually dead due to this.

    Forks can be found from GitHub as well as on here. As for why that is generally due to lack of activity on the original code base.
     
  20. MrChuck

    MrChuck TrainBoard Member

    27
    6
    2
    I'm going to post a new topic summarising what I've done so far rather than keep adding to this thread.
     
    Atani likes this.

Share This Page