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<@U016HSALFAN> So something I've noticed (and agai...
# caravel
t
@User So something I've noticed (and again now in new caravel) is that only the two first vertical 
met4
stripes get exported as "power pads" and so when generating the 
met5
straps at the top level (
user_project_wrapper
here), then only those get vias and connected.
Other issues I notice is that (1) I don't really want rails to be generated by the wrapper 😕 fills up 
met1
for no reason really. And (2) I need to generate 
met5
inside my project (which is inside the wrapper) to have the SRAM powered.
Sor for (2) my current work around is ... I aligned the grid generated by the wrapper with the one I generate internally.
a
@tnt: So, the whole power grid not being exported is a pdngen limitation that I reported months ago at https://github.com/The-OpenROAD-Project/OpenROAD/issues/215... I spent a considerable amount of time yesterday trying to make 
dbBPin
support multiple 
dbBox
, but I had to switch to some other task. If you wanna give it a go, I attached what I have so far. (@Matt Liberty/@mehdi, could you help me find out what's wrong? I think the issue is that I can't seem to populate the 
dbSet
properly.)
multi_boxes.patch
@tnt: The wrapper won't interfere for sure with whatever you're trying to do. At most it will take 2.4um from each side of your core area; you will have to generate your own rails/stripes and manage power on your own. If you wanna have a look and give feedback before this gets merged into the mainstream repo, check https://github.com/ax3ghazy/caravel/blob/new_wrapper/def/caravel.def.
t
Wait, doesn't that DEF have a few met4 traces going right in the middle of the user are ?
a
Right in the middle is a large obstruction resembling the project; there should be even more obstructions covering around the pins even, or that the pins should extend slightly outside the area.
t
Ok, yes I see. And to what extent can I configure that ring ? Like can I change the pitch etc to align to my grid ? Also I only need the core power AFAIK, so can I drop the other ? (by "can I" I mean, is it allowed, I see the script and how to change those)
a
So, what I think I can guarantee is that those rings (the rings only, not the stripes connecting to them), will be connected to the right power pads from the outside. Since the rings are technically outside the boundaries (defined by DIEAREA), then I think they shouldn't be touched. However, if you are not happy with the * stripe *pitches, then you can create your own that connect to the same exact core ring.
Why would you like to remove the other power rings?
t
Nope, I'm good with leaving the rings as is.
So having those fixed and then just putting straps where I want to connect to them is fine.
m
@User @User fyi, could you please take a look the pdngen issue above.
a
Yes, but then I need to take care not to use vias when connecting to the ring from the outside; otherwise, they may overlap with the vias you're creating.
t
@Ahmed Ghazy Mmm, can you connect to them through 
met3
?
But if allowing customizing pitch is annoying, I can deal with that some other way, I could make a power ring around the core or just wire stuff up with a custom script.
@Ahmed Ghazy Is that pushed on develop now ?
a
@tnt: The 
met3
solution would work for the vertical met4 stripes, but not the met5 ones. For now, if possible, try to stick with the current pitch (or a multiple of it), but I will also try to avoid vias while power-routing.
I can connect planarly using met4/met5 from the sides; will see how that goes.
t
I see you also got a solution to export the whole power grid.
(or a work around at least)
a
@tnt: I don't really like it, and it doesn't seem like valid DEF, but klayout and magic didn't complain, so can keep until we find the proper solution.
Copy code
- vccd1 + NET vccd1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 2905520 1759840 ) N + LAYER met4 ( -800 -1773960 ) ( <tel:8001773960|800 1773960> ) ;
    - vccd1 + NET vccd1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 2805520 1759840 ) N + LAYER met4 ( -800 -1773960 ) ( <tel:8001773960|800 1773960> ) ;
    - vccd1 + NET vccd1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 2705520 1759840 ) N + LAYER met4 ( -800 -1773960 ) ( <tel:8001773960|800 1773960> ) ;
    - vccd1 + NET vccd1 + DIRECTION INPUT + USE SIGNAL + FIXED ( 2605520 1759840 ) N + LAYER met4 ( -800 -1773960 ) ( <tel:8001773960|800 1773960> ) ;
t
Speaking of which ... is there a DEF format reference somwhere ?
a
I usually use this one: http://www.ispd.cc/contests/18/lefdefref.pdf (LEF/DEF 5.7).
👍 1
t
@Ahmed Ghazy So can we use any pitch ?
a
@tgingold: I don't recommend that for now.
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