Synchronizing multiple USB controllers to reduce power

An integrated circuit comprising:

• a first host controller interface comprising:
• a first frame counter providing a frame count output;
• a second host controller interface comprising:
• a frame count input coupled to the frame count output of the first frame counter;
• a mapping circuit coupled to the first host controller interface and the second host controller interface;
• a first bus port coupled to the mapping circuit;
• a second bus port coupled to the mapping circuit;
• and
• an interface circuit to provide memory read requests to a memory and to receive information from the memory, the interface circuit coupled to the first host controller interface and the second host controller interface.

A method of controlling a plurality of buses comprising:

• with a first host controller interface:
• receiving a first start command;
• providing a plurality of bits of a first frame count signal to a second host controller interface;
• and
• providing a first start of frame signal to a first bus;
• and
• with a second host controller interface:
• receiving a second start command;
• receiving the plurality of bits of the first frame count signal from the first host controller interface;
• generating a second frame count signal;
• comparing the plurality of bits of the first frame count signal to a plurality of bits of the second frame count signal;
• and
• when the plurality of bits of the first frame count signal match the plurality of bits of the second frame count signal, providing a second start of frame signal to a second bus.