PM7366-PI datasheet(268/286 Pages) PMC

268 / 286 page

RELEASED

PM7366 FREEDM-8

DATA SHEET

PMC-1970930

ISSUE 4

FRAME ENGINE AND DATA LINK MANAGER

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

255

The PCI Bus Request Cycle Diagram (Figure 32) illustrates the case when the initiator is

requesting the bus from the bus arbiter.

When the FREEDM-8 is the initiator, it requests the PCI bus by asserting its REQB output to the

central arbiter. The arbiter grants the bus to the FREEDM-8 by asserting the GNTB line. The

FREEDM-8 will wait till both the FRAMEB and IRDYB lines are idle before starting its access on

the PCI bus. The arbiter can remove the GNTB signal at any time, but the FREEDM-8 will

complete the current transfer before relinquishing the bus.

Figure 32 – PCI Bus Request Cycle

PCICLK

REQB

GNTB

FRAMEB

The PCI Initiator Abort Termination Diagram (Figure 33) illustrates the case when the initiator

aborts a transaction on the PCI bus.

An initiator may terminate a cycle if no target claims it within five clock cycles. A target may not

have responded because it was incapable of dealing with the request or a bad address was

generated by the initiator. IRDYB must be valid one clock after FRAMEB is deasserted as in a

normal cycle. When the FREEDM-8 is the initiator and aborts the transaction, it reports the error

condition to the PCI Host.

Figure 33 – PCI Initiator Abort Termination

PCICLK

FRAMEB

123

TRDYB

DEVSELB

IRDYB

PM7366-PI Datasheet(PDF) 268 Page - PMC-Sierra, Inc