Sun Microelectronics
89
7. UltraSPARC External Interfaces
7.4.3.4 Arbitration Timing
Figures 7-12 through 7-18 illustrate the arbitration protocol timing. They also
show how SYSADDR ownership changes from requestor to requestor.
The figures show the minimum arbitration latencies, which are as follows:
•
0 cycles if UltraSPARC or SC is C
URRENT
D
RIVER
(F
IGURE
7-11)
•
1 cycle if UltraSPARC is the L
AST
P
ORT
D
RIVER
(Figure 7-12)
•
2 cycles if not the L
AST
P
ORT
D
RIVER
(Figure 7-13)
•
4 cycles if the C
URRENT
D
RIVER
must be forced off (Figure 7-14)
Figure 7-12 shows the timing in a uniprocessor system, with the UltraSPARC
driving back-to-back packets in the absence of a request from SC.
Figure 7-11
Uniprocessor: Back-to-Back Packets—No SC Request
Figure 7-12 shows the timing for a single UltraSPARC driving back-to-back pack-
ets in the absence of another request.
Figure 7-12
Arbitration: Back-to-Back Packets—No Other Requests
Req<0>
SYSADDR
Addr_Valid<0>
Cycle 0
Cycle 1
Cycle 0
Cycle 1
0
0
0
0
0
L
AST
P
ORT
D
RIVER
Req<0>
Req<1>
SYSADDR
Addr_Valid<0>
Addr_Valid<1>
Cycle 0
Cycle 1
Cycle 0
Cycle 1
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com