82375EB datasheet(90/131 Pages) INTEL

90 / 131 page

82375EBSB

5421 REQ

And GNT

Rules

Figure 22 illustrates basic arbitration Once asserted GNT

may be negated according to the following rules

1 If GNT

is negated at the same time that FRAME

is asserted the bus transaction is valid and will

continue

2 One GNT

can be negated coincident with another being asserted if the bus is not in the idle state

Otherwise a one clock delay is incurred between the negation of the current master’s GNT

and assertion

of the next master’s GNT

to comply with the PCI specification

3 While FRAME

is negated GNT

may be negated at any time in order to service a higher priority master

or in response to the associated REQ

being negated

4 If the MEMREQ

and MEMACK

are asserted once the PCEB is granted the PCI Bus the arbiter will not

remove the internal grant until the PCEB removes it’s request

290477 – 64

Figure 22 Basic Arbitration

5422 Back-to-Back Transactions

Figure 23 illustrates arbitration for a back-to-back access There are two types of back-to-back transactions by

the same initiator those that do not require a turn-around-cycle (see Section 5131 Turn-Around-Cycle

Definition) and those that do A turn-around-cycle is not required when the initiator’s second transaction is to

the same target as the first transaction (to insure no TRDY

contention) and the first transaction is a write

This is a fast back-to-back Under all other conditions the initiator must insert a minimum of one turn-around-

cycle

During a fast back-to-back transaction the initiator starts the next transaction immediately without a turn-

around-cycle The last data phase completes when FRAME

is negated and IRDY

and TRDY

are assert-

ed The current initiator starts another transaction on the same PCICLK that the last data is transferred for the

previous transaction

82375EB Datasheet(PDF) 90 Page - Intel Corporation

82375EB Datasheet(HTML) 90 Page - Intel Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL