asix

Nix flake bundling PDKs, tapeout flows, and verification tooling for silicon.

PDKs

GF180MCU

GlobalFoundries 180nm process (gf180mcuD variant via wafer-space). Includes standard cells, tech LEF, GDS, Verilog, SPICE, and KLayout DRC/LVS rule decks. Fab slot definitions and seal ring metadata are exposed through passthru for tapeout integration.

Sky130

SkyWater 130nm process, HD standard cell library (via google/skywater-pdk). Provides LEF, GDS, Verilog, and SPICE. Note that liberty timing generation requires an open_pdks build — this package provides physical views only.

Overriding PDK configuration

PDK packages accept arguments for key configuration fields:

gf180mcu-pdk.override {
  cellLib = "gf180mcu_fd_sc_mcu9t5v0";
  siteName = "GF018hv5v_mcu_sc9";
}

Tapeout

asix.mkTapeout provides a generic RTL-to-GDS flow using Yosys, OpenROAD, and KLayout. It supports both flat and hierarchical (macro-based) builds.

my-tapeout = pkgs.asix.mkTapeout {
  ip = myIp;                  # Derivation with RTL + synth/PnR scripts
  topCell = "MySoC";
  pdk = pkgs.gf180mcu-pdk;
  clockPeriodNs = 20;

  # Die dimensions from fab slot
  fabSlot = "1x1";

  # Or explicit dimensions
  # dieWidthUm = 3932;
  # dieHeightUm = 5122;

  # Optional hierarchical hardening
  macros = [ "Core" "Cache" ];
};

Intermediate stages (topSynth, topPnr, macroDerivations) are exposed via passthru.

Verification

asix.mkVerify runs GDS physical verification — structure checks, fab precheck DRC, detailed DRC, and Verilog-to-SPICE conversion for LVS readiness.

my-verify = pkgs.asix.mkVerify {
  tapeout = my-tapeout;

  # Optional overrides
  # gatingDrc = false;        # Don't fail on DRC violations
  # enableLvs = false;        # Skip SPICE generation
};

Usage

{
  inputs.asix.url = "github:MidstallSoftware/asix";
}

Use the overlay to pull everything into your nixpkgs:

nixpkgs.overlays = [ asix.overlays.default ];

This gives you pkgs.gf180mcu-pdk, pkgs.sky130-pdk, and pkgs.asix.{mkTapeout, mkVerify}.

Community

• Discord: Join the server
• Contact: inquire@midstall.com