DCC++EX on UNO - what is going on ?

Peter Krebs Nov 24, 2021

  1. Peter Krebs

    Peter Krebs TrainBoard Member

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    Hi,

    I am new to the DCC environment and I am trying to work things out. I have uploaded DCC++EX onto a new (genuine) UNO R3 and things behave rather odd. I can connect and talk to the UNO using JMRI or a terminal app, but I receive these errors as soon as I send <1>.

    SC.png
    After I issue power off <0>, <c> will report 0 current. There is no motor shield or anything else attached at this point of time, and the UNO is powered through the USB. When I use a NANO (clone) all is well and no messages appear. Is this a configuration issue, or is my UNO ready for the bin ?

    Cheers,

    Peter
     
  2. Sumner

    Sumner TrainBoard Member

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    How about connecting the motor shield and testing that way?
    Sumner
     
  3. Kuba

    Kuba TrainBoard Member

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    Very similar symptoms occur when you run sketch on a bare Arduino board without installing the motor shield. There is no current signal, because the ADC input of the microprocessor is disconnected, it hangs in the air.
     
  4. Ash

    Ash TrainBoard Member

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    The default configurations include pins A0/A1 for current sensing and overcurrent reporting/shutdown. If you want to run without current sensing enabled, you can jumper pins A0/A1 to GND.
     
  5. Peter Krebs

    Peter Krebs TrainBoard Member

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    Thanks for the replies. My motor shield does not have current sensors. I have connected the shield and have created two entries in the config.h, setting the sensor pins to UNUSED_PIN. The shield works fine now, but I obviously get a warning at boot-up that there is no short circuit protection. I will use separate ICS714 current sensors on pins 0 and 1 to fix that. The error messages are/were caused by the 'floating' analog inputs (A0/A1), which will take on spurious values create by noise. I could have tied them to VREF or GND, as suggested. It works ok now, and I have learned something in the process ...
     

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