pdgen remove stripes with [WARNING PDN-0200] Removing floating shape:

[titan73]

Based on the example at the bottom of https://openroad.readthedocs.io/en/latest/main/src/pdn/README.html.

I did the following floorplan with the .def containing the power pins:

read_def -floorplan_initialize floor.def
set fp_area [ord::get_die_area]
initialize_floorplan -die_area $fp_area -core_area $fp_area -site CORECUBRICK

add_global_connection -net VDDD -pin_pattern {^VDDD$} -power
add_global_connection -net GNDD -pin_pattern {^GNDD$} -ground

set_voltage_domain -power VDDD -ground GNDD

define_pdn_grid -name "Core"
add_pdn_ring -grid "Core" -layers {metal4B alucap} -widths 5.0 -spacings 2.0 -core_offsets 4.5 -connect_to_pads

add_pdn_stripe -followpins -layer metal1 -extend_to_core_ring

add_pdn_stripe -layer metal4B -width 0.48 -pitch 56.0 -offset 2.0 -extend_to_core_ring
add_pdn_stripe -layer alucap -width 1.40 -pitch 40.0 -offset 2.0 -extend_to_core_ring

add_pdn_connect -layers {metal4B alucap}
add_pdn_connect -layers {alucap metal4B}

pdngen

The sroutes and the ring are created but not the stripes and I get the the warnings:

[WARNING PDN-0200] Removing floating shape: GNDD (1.7600, -9.5000) - (2.2400, 821.3000) on metal4B
[WARNING PDN-0200] Removing floating shape: VDDD (29.7600, -16.5000) - (30.2400, 828.3000) on metal4B

Is there something more to do to connect these shapes?

[titan73]

Also note that the related power pins imported the from .def are removed.

[maliberty]

Can you provide a test case? Its hard to say much from just the output

[titan73]

I asked my hierarchy how to deal with that. Since this is research stuff I don't know how it will end up as open source eda is pretty new to my company. But since we're creating a position for a PhD on that subject, that would probably ease things. In the meantime I'm digging into the code of pdn.

[gadfort]

Additional thoughts:

1. Do you have a connect statement from metal1 to metal4B/alucap without it the rings would be floating and end up getting removed.
2. If there is no room to place a via on the ring corners, that would also cause some issues. You may want to check the vias available to see what is available.

[titan73]

The power ring was not removed as the vias between metal4B and alucap were created. It was only the vias of the power grid that were not created getting the stripes to be removed.

How do I check what vias are available?
In the techno .lef I have 3 vias rules between metal4B and alucap.

On monday, I'll try to use the power ring width for the stripes also to see if I can get the vias created.

[titan73]

I've tested with bigger stripes width and this fixed the issue. Vias were created and thus stripes were not removed.
Thanks for the support.

[maliberty]

I'm glad you found a solution