ATT3042 Просмотр технического описания (PDF) - Unspecified

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ATT3042

Field-Programmable Gate Arrays

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Data Sheet

February 1997

ATT3000 Series Field-Programmable Gate Arrays

Programmable Interconnect

Programmable interconnection resources in the FPGA

provide routing paths to connect inputs and outputs of

the IOBs and logic blocks into logical networks. Inter-

connections between blocks are composed from a two-

layer grid of metal segments. Specially designed pass

transistors, each controlled by a configuration bit, form

programmable interconnect points (PIPs) and switching

matrices used to implement the necessary connections

between selected metal segments and block pins.

Figure 7 is an example of a routed net. The ORCA

Foundry Development System provides automatic rout-

ing of these interconnections. Interactive routing is also

available for design optimization. The inputs of the logic

or IOBs are multiplexers which can be programmed to

select an input network from the adjacent interconnect

segments. Since the switch connections to block inputs

are unidirectional (as are block outputs), they are

usable only for block input connection and not routing.

Figure 8 illustrates routing access to logic block input

variables, control inputs, and block outputs.

Three types of metal resources are provided to accom-

modate various network interconnect requirements:

s General-purpose interconnect

s Direct connection

s Long lines (multiplexed buses and wide-AND gates)

Figure 8. CLB Input and Output Routing

Figure 7. Example of Routing Resources

Lucent Technologies Inc.

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