K8055 User Interface is a Mac OS X based Cocoa application for controlling the Velleman K8055 USB interface. Included is a static library which can be used for developing other applications and closely replicates the Velleman Windows .DLL functions.
Didn't work for me at first. The interface fails in K8055 at // Open the device for exclusive access err = (*USBInterfaceInterface)->USBInterfaceOpen(USBInterfaceInterface); with kIOReturnExclusiveAccess This is because the "empty" device driver doesn't work. Using this piha/k8055-mac-codeless-kext from github as a no-code driver, the interface app works fine. Anyway, there's no ok error handling if things go wrong, just return statements without closing the device etc. - keep that in mind. A nice starting point for a driver.