Activity Forums Questions & Troubleshooting USB Link Controllino make reset when RaspPI3 ShutDown

  • USB Link Controllino make reset when RaspPI3 ShutDown

  • Vax

    December 15, 2022 at 8:28 am

    Good morning, sorry for my poor English, I’m French !

    All is in the title.

    I use Controllino Maxi linked with Raspberry Pi3 by USB.

    I use Pi with touchscreen for MMI (IHM in french). When I shutdown the Pi, the Controllino make reset and I try to understand how and why.

    As I read in the User manuel :

    The main function of the USB port is to program the CONTROLLINO. Inside the CONTROLLINO there is a USB to UART converter which generates a virtual COM-Port on the PC. You can also use this port to give data to a terminal or another program.”

    Maybe this USB to UART converter make a DTR signal when the USB link is closed…

    Tanks a lot by advance.


    • This discussion was modified 1 year, 6 months ago by  Vax. Reason: add informations
  • Lukas

    March 15, 2023 at 4:28 pm

    Hi Xavier,

    yes, this is normal behaviour of the Arduino USB interface. This feature (reset based on DTR) is used during the programming. DTR is toggled by the system when the Virtual USB port is open/closed and it is very hard to avoid that.

    But there exists kind of a hack how to prevent this behaviour. Interconnect 5V a and RESET signals at pinheader X1. (But then you must not use the reset button!)

    Please take it really as an unofficial hack. It is not a solution for some product, or industrial application.

    Best regards,


    • This reply was modified 1 year, 3 months ago by  Lukas.
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