US Patent 7340544 Method of using bus and bus interface

A method of using a bus, includes: determining whether a subject unit among a plurality of units corresponding to masters obtaining a bus use permission from an arbiter uses the bus as a master to transfer data to/from a first unit corresponding to a slave; and converting the first unit into a master when the subject unit does not use the bus in order to allow the first unit to use the bus as a master, when the subject unit is determined not to be using the bus.