Low-Power Extended USB Flash Device Without Polling

摘要

An extended Universal-Serial Bus (EUSB) host enters a suspend mode rather than poll an EUSB device that is busy performing a memory or other operation. Power is saved since polling is avoided. The busy EUSB device sends a not-yet NYET signal back to the EUSB host to instruct the host to enter the suspend mode. When the EUSB device is ready to continue transfer with the host, the EUSB device wakes up the host by sending a ready RDY signal back to the host. The NYET and RDY signals may be tokens or flags in serial packets sent over a full-duplex connection to the host with two sets of differential pairs. Transfers may be re-started by the host after suspension once the requested data is read from flash memory, or space is made available in a sector buffer by completing earlier writes to flash memory.