Emergency Stop Question


I have been using my CR-10S with the factory default board (melzi) running Marlin 1.x.x. When pressing the Emergency Stop button on Repetier Server WebUi print would stop as normal and then the machine would return to Marlin waiting to be used again.

Now recently i have upgraded to a 32bit board (BigTreeTech SKR 1.4 Turbo) and with that i had to upgrade to Marlin 2.0.6. as well. I noticed that now if i press the Emergency Stop button printer stops as intended however on the LCD screen i see the message that the printer needs to be reset (power cycled) to continue to do anything. 

As mentioned above in the original setup this step was not needed and i would really like to get back to that way of working as this extra step is a bit unecessary for me.

I don't know if this change in behaviour is because of the SKR 1.4 board or because of Marlin 2.x.x or maybe both but if someone has any advice on what i should change to get back to the original Emergency Button behaviour i would appriciate it.



  • Server uses a dual approach for emergency to be fast. It sends M112 and then toggles DTR/RTS to force hardware reset. I think the SKR boards do not reset on toggle.

    Try sending M112 in console and see if that is the way you see it now. Then you know it is that it does not act on M112 as expected.
  • edited August 2020
    Yep. When running M112 from console same thing happens. 

    I played around a bit with the RTS/DTR settings since i also initially had an issue with Repetier Server not connecting to the board with the same RTS/DTR settings (Low to High on both) i had for the Melzi board. After switching RTS to Low and DTR to high connection could be established.

    Now i did a test for all possible permutations to see if maybe one of them would work with the emergency stop but unfortunately neither works. All just stay on the Emergency Stop message and a power cycle needs to be made for the board to restart and repetier server being able to reconnect again. :(

    Also for reference these are the results for trying to connect repetier server to the board with different RTS/DTR combinations:

    RTS = Low, DTR = Low to High  --> Connects
    RTS = Low, DTR = High --> Connects
    RTS = Low, DTR = Low --> Not Connected
    RTS = Low, DTR = High to Low --> Not Connected

    RTS = High, DTR = Low to High --> Connects
    RTS = High, DTR = High to Low --> Not Connected
    RTS = High, DTR = Low --> Not Connected
    RTS = High, DTR = High --> Connects

    RTS = Low to High, DTR = High  --> Connects
    RTS = Low to High, DTR = Low  --> Not Connected
    RTS = Low to High, DTR = Low to High  --> Not Connected
    RTS = Low to High, DTR = High to Low  --> Connects

    RTS = High to Low, DTR = Low  --> Not Connected
    RTS = High to Low, DTR = High  --> Connects
    RTS = High to Low, DTR = High to Low --> Connects
    RTS = High to Low, DTR = Low to High --> Not Connected

  • I think that board has a native usb connection and not a usb serial converter that uses DTR to reset. Same is native port on due boards which have no influence as there is no pin output to reset.

    Thanks for the table, also I miss a logic when it connects or not. Normally only end state should matter but when it toggles the versions working also change. Will further investigate here.
  • Thanks for checking. Also regarding your USB comment. BigTreeTech has some pretty nice technical documentation available for their board on their github. Maybe that has some usefull info for you. You can find the info here: https://github.com/bigtreetech/BIGTREETECH-SKR-V1.3/tree/master/BTT%20SKR%20V1.4
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