Appendix B. Service Calls

Table of Contents

Service_USB 0 - Pipe released - Indicate pipe release
Service_USB 1 - Pipe requested exclusively - Exclusive access to pipe requested
Service_USB 2 - Release USB device configuration setting - Application request to release USB device configuration setting
Service_USB 3 - Release USB device interface setting - Application wants to release USB device interface setting
Service_USB 4 - Change transfer capacity - Claim/release USB transfer capacity
Service_USB 5 - Change USB power use - Claim/release USB power capacity
Service_USB 7 - Sub host controller driver has been started. - Used for communications between USB Host Controller drivers. Shows that a sub host controller driver has been started.
Service_USB 8 - Sub host controller removed - Used for communications between USB Host Controller drivers. Shows that a sub host controller driver has been removed.
Service_USB 16 - USB system module started - Used to show other applications that a Module belonging to the USB-System has been started. It can be also launched again at an arbitrary point of time to cause a defined set of actions by other modules.
Service_USB 17 - USB system module stopped - Used to indicate to other applications that part of the USB system has shut down.
Service_USB 18 - USB system module pre-stop - Used to indicate to other applications that part of the USB system is stopping.
Service_USB 19 - Resume halted shutdown - Used to resume a claimed stop service when ready to continue.
Service_USB 32 - HUB state changed - Broadcast by the Hub Class driver module to inform other programs about changes inside a hub or about changes about device states detected by the Hub.
Service_USB 33 - USB host controller driver Hub status change - Broadcast by an USB host controller driver to inform other applications about events inside USB host controller driver Hubs.

The usb system uses a service call (&80C00) to inform client programs of certain events. Register 0 is used as a reason code. Other registers depend on the reason code.

Note

Many of these service calls are now considered obsolete and have been superseded by the USB messaging system Appendix D