Architecture enabling code overlay using a dedicated endpoint

摘要

A USB function device (14) for coupling to a USB host (12). The USB function device (14), comprises circuitry (32) for providing a capability to the USB host, where the circuitry for the capability comprises an address space. The USB function device further comprises a USB interface circuit (136) coupled between the USB host (12) and the circuitry (32) for providing a capability to the USB host. The USB interface circuit comprises a memory area (106) comprising a code overlay endpoint (106₁) accessible to the USB host for writing two or more code blocks to the code overlay endpoint. The USB interface circuit further comprises circuitry (150-163) for communicating a first of the code blocks from the code overlay endpoint to the address space and for subsequently communicating a second of the code blocks from the code overlay endpoint to the address space. The circuitry for communicating is operable to communicate a code block from the code overlay endpoint to the address space after a start-up time of the USB function device.