USB transaction translator and a micro-frame synchronization method adaptable to an USB in isochronous transaction

摘要

The present invention is directed to a universal serial bus (USB) transaction translator and a micro-frame synchronization method. A device interface is coupled to a device via a device bus, and a host interface is coupled to a host via a host bus, wherein the host USB version is higher than the device USB version. At least two buffers configured to store data are disposed between the device interface and the host interface. A controller stores the data in the buffers alternately. A start-of-frame (SOF) counter is used to count the SOF packets, wherein the counting value of the SOF counter is compared to a predefined value. Specifically, the controller resets a SOF timer for sending the SOF packet when the counting value achieves the predefined value or is greater than the predefined value, such that the SOF packet and an isochronous timestamp packet (ITP) from the host are sent at the same time. Further, the controller delays the sending of the SOF packet for a period of time according to the ITP from the host.