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Create a custom app API/Interface for controlling UMDF (IddCx) driver?

scott_smithscott_smith Member Posts: 75

I want to add a fairly straightforward interface/API to my UMDF (IddCx) display driver for use by apps. Something like this...:

int     GetConnectorCount();
bool    IsMonitorConnected(int connectorIndex);
HRESULT ConnectMonitor(int connectorIndex);
HRESULT DisconnectMonitor(int connectorIndex);

No need to read or write a data stream; just a few simple functions to query and manage state.

I've been looking for examples of this in the Windows Driver Samples, but all I've found are examples where IOCTLs are intercepted.

  • I can't recall whether there was an issue with intercepting IOCTLs in an IddCx driver
  • I thought I saw something about creating a COM interface at some point, but I can't find any examples

Can anyone help clarify what my options are, and maybe point to an example or some documentation?

Scott Smith
Windows Developer since 1989


  • Doron_HolanDoron_Holan Member - All Emails Posts: 10,584

    You should not create an externally activatable COM interface in a UMDF driver (v1 or 2). The IddCx sample and docs do not talk about normal IO in an IddCx client driver. It should be a simple experiment in your AddDevice routine:
    1) create a device interface
    2) create a WDFQUEUE to handle IOCTLs

    and in your app, enumerate the device interface, open it, and try to send an IOCTL and see if it shows up in your driver.

  • scott_smithscott_smith Member Posts: 75

    Awesome! Thanks!

    Scott Smith
    Windows Developer since 1989

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