Getting started

This repository is not a PDK. It is the thin layer of customization that sits between the sky130A PDK and a design: the corner definitions, the make targets, the magic and xschem setup, and the scripts that hold the flow together.

You never work in this repository. You clone it beside an IP repository, which symlinks it as tech, and everything here is reached through that symlink.

1. Get the tools

Two ways.

The container. wulffern/aicex has magic, xschem, netgen, ngspice, KLayout and the PDK already installed, at the paths everything here assumes (/opt/pdk/share/pdk, /opt/eda/bin). This is what CI uses, so a local run matches CI exactly.

From source. make/tools_install.make builds the lot on Ubuntu 20.04:

make -f tech_sky130A/make/tools_install.make

Either way, set the two environment variables everything depends on, see bash/bashrc:

export PDK_ROOT=/opt/pdk/share/pdk    # or /usr/local/eda/share/pdk
export PDK=sky130A

Check it worked:

ls $PDK_ROOT/$PDK/libs.tech/magic/sky130A.magicrc

If that file is not there, nothing below will run.

2. Get the python tools 

python3 -m pip install cicconf cicsim cicpy

cicconf clones dependencies and creates IP repositories, cicsim runs simulations, and cicpy transpiles generated layout. pandas and click are needed by some of the scripts, and gdstk by render_gds.py.

3. Make an IP

From the directory that holds your repositories, with a config.yaml naming the project, the technology and the template to use:

options:
  project: JNW
  technology: SKY130A
  template:
    ip: ../tech_sky130A/cicconf/jnw.yaml

cd ~/work
cicconf newip bias

The IP is named <project>_<name>_<technology>, so that gives JNW_BIAS_SKY130A in a directory called jnw_bias_sky130a. Add --ip <path> to use a template other than the one in config.yaml, and see cicconf/ for what the four here differ in.

That creates the repository, writes the CI workflows, makes the first commit, and lays down the symlinks the flow depends on:

~/work/
├── tech_sky130A/           this repository
├── cpdk/                   borders and shared symbols
├── jnw_tr_sky130A/         standard cells
├── jnw_atr_sky130A/        analog transistor library
└── jnw_bias_sky130a/
    ├── tech -> ../tech_sky130A
    ├── config.yaml         what to clone
    ├── info.yaml           who you are, what the docs say
    ├── design/JNW_BIAS_SKY130A/
    │   ├── JNW_BIAS.sch          ${CELL}, the IP name less its last segment
    │   └── JNW_TR_SKY130A -> ../../../jnw_tr_sky130A/design/JNW_TR_SKY130A
    ├── work/               where you run make
    ├── sim/                where you run cicsim
    └── media/

On an IP that already exists, clone its dependencies instead:

cd jnw_bias_sky130a
cicconf --rundir ../ --config config.yaml clone --https

4. Check the flow works

Everything in make/core.make is run from work/:

cd my_ip/work
make help          # the built-in summary
make xview         # open the schematic in xschem
make xsch          # netlist it

make help prints the target list. Adding -n to any target shows the commands it would run without running them, which is the fastest way to understand what a target actually does:

make xsch LIB=MY_IP_SKY130A CELL=MY_CELL -n

Where to go next