PCI arbiter doubts

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Hi all,

 I have some basic doubts on PCI arbiter.

 1)how is the framen controlled -- i guess it is a shared resource on
the PCI bus wher all the devices  sitting on the PCI bus have access to
it.

 2)If a request is received from a device on PCI bus ,should the grant
be issued immediately or should the PCI arbiter wait until the framen
is dropped (asserted).

  3)If a request is received from a device on PCI bus , but the framen
is not dropped at all.how should the PCI arbiter react to this
condition.

Regards,
Praveen


Re: PCI arbiter doubts
Hi Praveen,

1) FRAME, REQ, and GNT lines are *not* shared between different
resources. There is a FRAME#(A), FRAME#(B), REQ#(A), REQ#(B), GNT#(A),
GNT#(B), there is one of per bus master.

2) FRAMEN# is asserted (dropped) by the bus master after it receives a
GNT#, it must be done as soon as possible for the bus cycle to begin.
If the GNT# is desserted prior to the bus mater asserting FRAMEN# then
it looses bus ownership and has to reabitrate. FRAMEN# is not asserted
prior to GNT#.

3) see #2


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