Hi @User @User I have a question about tapeout requirements for designs using caravel. We are working on a mixed signal chip with a small amount of digital that we’re building up manually (not using openlane) but we want the caravel harness for its ESD protection (our analog inputs are slow). Should we follow the tapeout requirements for caravan then or is there a different set of requirements for mixed signal design with custom analog and digital? Thanks!

@User: Specifically, the question is how does the precheck and tapeout work for an analog project that is using the

caravel

chip instead of

caravan

, but just using the analog I/O on the GPIO pads. Ideally, that situation calls for a user project wrapper layout that is similar to the analog project wrapper but compatible with the

caravel

user project wrapper pinout. We don't currently have such a thing. @User: Would it be possible to use

caravan

and just not use the 11 analog pads, or would you run out of pins that way? Otherwise, it may work if you use

caravel

and keep the power rings and pin connections from the

caravel_user_project

empty wrapper layout, and avoid routing in the area of the power rings other than metal4 or metal5 as needed to make the power connections. But I think there are parts of the precheck that assume there are files produced by Openlane, so I'm not sure if such a design is going to get rejected by precheck.

Thank you @User we are I/O limited and are planning to use all 38 GPIOs. We can limit ourselves to M4 and M5 for the power area, but I was worried because the caravel submission seemed to expect an openlane-generated reports directory that we won’t have.

Check with @User as to what you might need to do to get the project to pass submission. You might have to create some fake report files or something like that to make it work right.

Hi @User, bumping this thread up!

hi @User. we just discussed this and I believe you should be able to modify a user_project_example layout (e.g. the user_project_wrapper_empty.gds in the caravel repo) and submit a mixed signal design user the standard wrapper. you do need to provide a netlist for your user_project_wrapper. see the precheck documentation for more specifics. let me know if you have further questions.