Patent attributes
A particular problem for self-service devices incorporating USB devices (12) and a USB host (14) is that, when communication is lost between the USB host and one or more of the devices it is difficult (in particular situations) to reset those USB devices without manual intervention. We address that problem by using self-powered USB devices and/or bus powered devices connected to USB hubs, and by creating a power control interface (18) which is itself a USB device. That power control interface takes instructions from the USB host and is able to interrupt a power supply (20) to the USB devices to provoke automatic reset of those devices. Additionally, a watchdog application within the power control interface causes reset of that interface should it malfunction. Also, a master watchdog application at the USB host communicates with a slave watchdog application at the power control interface via a USB link. In the event of cessation of heartbeat signals between the master and slave the power control interface sends a hardware reset signal to the USB host.
