docs: Clarify correct usage of site PIPs #51
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mithro
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May 7, 2021
docs/device_resources.md
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| @@ -242,6 +242,10 @@ entered via the site port corresponding to the site pin. The first site wire | |||
| in the site will be the site wire attached to the output BEL pin of the site | |||
| port. From there site routing continues per above. | |||
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| It is important to note that site PIPs can only be used to access placed cells inside that site. Site PIPs cannot be used as general route-thrus, to route from site input to output. General route-thrus across entire sites should use tile pseudo PIPs as described below - even if a site pin is being validly used for one sink pin of a net that is located inside the site; site PIPs cannot also be used to leave the site again to reach other sinks. | |||
Signed-off-by: gatecat <[email protected]>
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clavin-xlnx
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May 7, 2021
mithro
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May 8, 2021
| PIPs. The site PIP would be used to route through the LUT in order to access | ||
| an associated flipflop input inside the site. The tile PIP would be used to | ||
| route across the entire site as part of the general, inter-tile, routing | ||
| problem. |
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I feel like this could do with a diagram, but I don't think we should block merging the description based on that.
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Agreed, happy to do a follow-up with one.
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Fixes #50 - hopefully this is an accurate summary of what we intend the contract to be and covers all the possibilities.