The USB1.1 PHY is an IP version of USB transceiver designed in standard logic to interface the physical layer of Universal Serial Bus. It receives data via DP and DM and transfers data to USB1.1 core via RCV, VM and VP, capable of transmitting and receiving serial data at full speed (12M bit/s). The serial interface engine (SIE) controls the state of USB1.1 PHY through the OEN signal. When in receiving mode, it receives data at the USB1.1 PHY output RCV, VM and VP; when in transmitting mode, it drives the USB1.1 PHY input VPO and VMO. Please note that the IP can only be used as device in crystalless mode, but either host or device in crystal and PLL mode. And the maximum data package on DP/DM is 64 bytes, longer package isn’t supported.