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Is it possible to reset/restart application without resetting USBD

Andreas3T

Hi,

We have a custom bootloader and a firmware, both use the USB CDC ACM. Is it possible to start the firmware without resetting the USB instance so Windows have a continuous COM "connection" , i.e. the COM port does not disappear and reappear. Is it also possible to restart the firmware in the same fashion?

Currently nrf_bootloader_app_start(); is used to start and restart the firmware.

Best Regards,
Andreas Öhman

  • 0

    It is the pull-ups on the D+ or D- lines (Depends on device speed) that determine if Windows re-enumerates.
    During device reset these typically are turned off, so Windows terminates the connection.

    If you are getting a different COM number on each cycle, you can assign a serial number, even if it is just "1", in your USB descriptor for the port. It will stop being a different COM port number on that USB hardware instance.

  • 0 in reply to bpaddock

    I'm getting the same COM number as intended, the issue is the temporary disappearance of the COM port.

  • +1 in reply to Andreas3T
    Is it possible to start the firmware without resetting the USB instance so Windows have a continuous COM "connection" , i.e. the COM port does not disappear and reappear.

    No. This is not supported.

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