System and method for assigning unique addresses to agents on a system

Abstract

A computer system including a bus master performs a method for automatically assigning addresses to agents on a bus. Addresses are automatically assigned so that a computer system user does not set physical or logical switches, either manually or through software programming. The system and method also automatically assign unique addresses to new devices that are inserted on the bus while the bus is operating, thereby supporting 'hot pluggable' devices. Slave agents are originally configured to operate at a class address. At the beginning of the method, a master determines whether any of the slaves reside at the class address. If so, then the master determines a new unique address and issues a Get Bitwise UID command to the slaves residing at the class address. Each of the slaves receives the Get Bitwise UID and responsively transmits a hardware identification (UID) in a loop of bitwise byte transmissions. One slave successfully transmits the hardware identification (UID) while the other individual slaves detect transmission errors during transmission of the hardware identification (UID) and terminate transmission upon the error detection. The unsuccessful slaves, if previously residing at a unique address, revert to the class address. The master receives the hardware identification (UID) of the successfully transmitting slave and issues a Set Address command in combination with the hardware identification (UID) and the new unique address to all slave agents at the class address. Only the slave agent with a hardware identification (UID) matching the UID of the Set Address command processes the Set Address command to completion and is assigned the address. The master uses the Get Bitwise UID command followed by the Set Address command in a loop to locate, identify and assign addresses to agents responding to a predetermined class address.