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IO_LOC_PAIRS not set for OBUFT with T input connected to net #403

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hannesha opened this issue Nov 21, 2022 · 0 comments · May be fixed by #494
Open

IO_LOC_PAIRS not set for OBUFT with T input connected to net #403

hannesha opened this issue Nov 21, 2022 · 0 comments · May be fixed by #494

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@hannesha
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I tried to use 3-state outputs in a project, but the outputs are not driven at all. Setting T to 0 drives the outputs as expected.

I created a minimal example on a basys3 board with two switches to reproduce this issue.

Looking through the files revealed that .IO_LOC_PAIRS is set to "NONE" for the affected OBUFT, in the .eblif file.
Manually setting .IO_LOC_PAIRS on the OBUFT makes it work as expected. I verified that the output is floating with a voltmeter.

I attached a archive with the example, a f4pga flow config, my conda list output, the .eblif files and yosys logfiles of the working and broken state.
example.tar.gz
mglb pushed a commit to antmicro/yosys-f4pga-plugins that referenced this issue Apr 3, 2023
@kbieganski
Fix plugin-only release CI (chipsalliance#403)
d405eee 
Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
@hannesha hannesha linked a pull request Apr 25, 2023 that will close this issue
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XDC: Add missing OBUFT primitive hannesha/yosys-f4pga-plugins
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@hannesha