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Many of these service calls are now considered obsolete and have been superseded by the USB messaging system Appendix D, USB Messaging System Messages