°Bus arbitration
scheme:
•A bus master wanting
to use the bus asserts the bus request
•A bus master cannot use
the bus until its request is granted
•A bus master must signal
to the arbiter after finish using the bus
°Bus arbitration schemes
usually try to balance two factors:
•Bus priority: the highest
priority device should be serviced first
•Fairness: Even the lowest
priority device should never
be
completely locked out from the bus
°Bus arbitration schemes
can be divided into four broad classes:
•Distributed arbitration
by self-selection: each device wanting the bus places a code indicating
its identity on the bus.
•Distributed arbitration
by collision detection: Ethernet uses this.
•Daisy chain arbitration:
see next slide.
•Centralized, parallel
arbitration: see next-next slide