Intel 1.00 GHz YK80542KC0013M Benutzerhandbuch

Produktcode

YK80542KC0013M

Datasheet

Signals Reference

During power-on configuration, the priority agent must assert the BR[0]# bus signal. All
symmetric agents sample their BR[3:0]# pins on asserted-to-deasserted transition of RESET#. The
pin on which the agent samples an asserted level determines its agent ID. All agents then configure
their pins to match the appropriate bus signal protocol as shown in

Table A-6

A.1.15

BREQ[3:0]# (I/O)

The BREQ[3:0]# signals are the symmetric agent arbitration bus signals (called bus request). A
symmetric agent n arbitrates for the bus by asserting its BREQn# signal. Agent n drives BREQn#
as an output and receives the remaining BREQ[3:0]# signals as inputs.

The symmetric agents support distributed arbitration based on a round-robin mechanism. The
rotating ID is an internal state used by all symmetric agents to track the agent with the lowest
priority at the next arbitration event. At power-on, the rotating ID is initialized to three, allowing
agent 0 to be the highest priority symmetric agent. After a new arbitration event, the rotating ID of
all symmetric agents is updated to the agent ID of the symmetric owner. This update gives the new
symmetric owner lowest priority in the next arbitration event.

A new arbitration event occurs either when a symmetric agent asserts its BREQn# on an Idle bus
(all BREQ[3:0]# previously deasserted), or the current symmetric owner deasserts BREQn# to
release the bus ownership to a new bus owner n. On a new arbitration event, all symmetric agents
simultaneously determine the new symmetric owner using BREQ[3:0]# and the rotating ID. The
symmetric owner can park on the bus (hold the bus) provided that no other symmetric agent is
requesting its use. The symmetric owner parks by keeping its BREQn# signal asserted. On

Table A-4. BR0# (I/O), BR1#, BR2#, BR3# Signals for 4P Rotating Interconnect

Bus Signal

Agent 0 Pins

Agent 1 Pins

Agent 2 Pins

Agent 3 Pins

BREQ[0]#

BR[0]#

BR[3]#

BR[2]#

BR[1]#

BREQ[1]#

BR[1]#

BR[0]#

BR[3]#

BR[2]#

BREQ[2]#

BR[2]#

BR[1]#

BR[0]#

BR[3]#

BREQ[3]#

BR[3]#

BR[2]#

BR[1]#

BR[0]#

Table A-5. BR0# (I/O), BR1#, BR2#, BR3# Signals for 2P Rotating Interconnect

Bus Signal

Agent 0 Pins

Agent 3 Pins

BREQ[0]#

BR[0]#

BR[1]#

BREQ[1]#

BR[1]#

BR[0]#

BREQ[2]#

Not Used

BREQ[3]#

Not Used

Table A-6. BR[3:0]# Signals and Agent IDs

Pin Sampled

Asserted on

RESET#

Arbitration ID

Agent ID Reported

BR[0]#

BR[3]#

BR[2]#

BR[1]#