How to Use Chisel? | Two Tools, One Name

Chisel is either a Scala-based hardware description language or Canonical’s Ubuntu package-slicing tool, and each works completely differently.

For the full breakdown, see our best Chisel Set guide.

The name “Chisel” points to two distinct open-source projects, and knowing which one you need is half the battle. The chipsalliance/chisel project is a hardware construction language embedded in Scala, used for designing digital circuits that generate synthesizable Verilog. Canonical Chisel, meanwhile, is a developer utility that extracts specialized Ubuntu packages by selecting only necessary slices. They share a name but share almost nothing else — different languages, different goals, different workflows.

Before you start, confirm which tool you actually need. Designing FPGA or ASIC logic? That’s the Scala Chisel. Building a minimal Ubuntu root filesystem? That’s Canonical Chisel. The steps below cover both, so you can go straight to the one that matches your project.

Using Chisel the Hardware Construction Language

Chisel lives inside Scala, so your first step is a working Scala environment. You write circuit descriptions as Scala code, and the Chisel library translates that code into a hardware graph that can generate synthesizable Verilog. The official documentation at chisel-lang.org/docs is the definitive starting point.

A minimal Chisel module looks like this:

import chisel3._

class Blinky extends Module {
 val io = IO(new Bundle {
 val led = Output(Bool())
 })
 io.led := true.B
}

The project targets ASIC and FPGA digital logic design, and the API documentation serves as the detailed reference for the source code. If you’re familiar with Scala, the learning curve is mostly about thinking in hardware terms — signals, clocks, and registers — rather than software control flow.

Using Canonical Chisel for Ubuntu Package Slices

Canonical Chisel builds compact, specialized Ubuntu root filesystems by pulling only the slices you actually need from the full package set. The official documentation at Ubuntu Chisel docs walks through the tutorial, common patterns, and CLI commands.

Install the latest version with the Go toolchain:

go install github.com/canonical/chisel/cmd/chisel@latest

After installation, you select slices and let Chisel assemble a minimal filesystem. Package slice definitions live in the canonical/chisel-releases repository, which is the official source of supported slices, and each Chisel release maps to a separate Git branch there.

One security detail worth noting: Chisel records package, slice, and file metadata so you get file-level integrity and traceability for whatever you build.

Which Chisel Fits Your Workflow?

Both are open-source with no paid tiers, and both are maintained actively.

FAQs

Do I need Scala to use Chisel for hardware design?

Yes. The hardware Chisel is embedded in Scala, so you write circuit definitions as Scala code. You don’t need deep Scala expertise, but basic familiarity with Scala syntax and build tools like sbt or Mill will make the setup far smoother.

Can Canonical Chisel replace the hardware Chisel?

No. Canonical Chisel builds Ubuntu root filesystems from package slices; the hardware Chisel generates Verilog for FPGAs and ASICs. They share a name but have zero functional overlap.

Where do Canonical Chisel’s package slices come from?

Slice definitions are maintained in the canonical/chisel-releases repository, which is the official supported source. Each Chisel release uses a corresponding Git branch to pin the exact slice set, keeping builds reproducible and traceable.