28
•
Operation Theorem
3. I_REQ & I_ACK Handshaking
valid data
D10~DI31
valid data
t1
t2
t5
t4t3
IN I_REQ
IN I_ACK
t
1
≥ 0ns t
5
≥ 60ns t
3
≥ 2 PCI CLK Cycle
t
2
≥ 0ns t
4
≥ 1 PCI CLK Cycle
Note: I_REQ must be asserted until I_ACK asserts, I_ACK will be asserted
until I_REQ de-asserts.
4. O_REQ as output data strobe
Out O_REQ
t
cyc
th
ts
D00~D031
valid datavalid data
t
s
≥ 19ns t
h
≥ 2 PCI CLK Cycles
T
cyc
≥ 500ns