chisel tutorial exercises and answers
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Chisel Tutorials (Release branch)

These are the tutorials for Chisel.

Chisel is an open-source hardware construction language developed at UC Berkeley that supports advanced hardware design using highly parameterized generators and layered domain-specific hardware languages.

Getting the Repo

$ git clone
$ cd chisel-tutorial
$ git fetch origin
$ git checkout release

Executing Chisel

Testing Your System

First make sure that you have sbt (the scala build tool) installed. See details in sbt.

$ sbt run

This will generate and test a simple block (Hello) that always outputs the number 42 (aka 0x2a). You should see [success] on the last line of output (from sbt) and PASSED on the line before indicating the block passed the testcase. If you are doing this for the first time, sbt will automatically download the appropriate versions of Chisel3, the Chisel Testers harness and Scala and cache them (usually in ~/.ivy2).

Completing the Tutorials

To learn Chisel, we recommend learning by example and just trying things out. To help with this, we have produced exercises with circuits (src/main/scala/problems) and their associated test harnesses (src/test/scala/problems) which have clearly marked places to complete their functionality and simple test cases. You can compare your work with our sample solutions in (src/main/scala/solutions) and (src/test/scala/solutions). This hierarchical organization and separation of circuits and tests is a good practice and we encourage you to understand it and use it in the future. Typically when you work on a problem you will have two open editor windows (vi, emacs, IDE, etc) one to edit the circuit and the other to edit the tests.

To speed things up, we will keep sbt running. To get started:

$ sbt


This should already work. Try

> test:run-main problems.Launcher Mux2


You can instantiate a module with val foo = Module(new Bar())

> test:run-main problems.Launcher Mux4


You can conditionally update a value without a mux by using when (cond) { foo := bar }

> test:run-main problems.Launcher Counter

Vending Machine

> test:run-main problems.Launcher VendingMachine


The type of memory that's inferred is based on how you handle the read and write enables. This is pretty much the same as how Xilinx and Altera infer memories.

> test:run-main problems.Launcher Memo


> test:run-main problems.Launcher Mul


> test:run-main problems.Launcher RealGCD

To check that all of your solutions are correct:

$ ./ all

To run all of our reference solutions:

$ ./ all

Note: ./, ./, ./ are convenience scripts to invoke tests

Learning More Chisel

In addition to the problems and the solutions, we have also provided some examples of more complex circuits (src/main/scala/examples) and (src/test/scala/examples). You should take a look at the source and test them out:

$ ./ all

The wiki attached to this repo contains more information on working with Chisel. Additional documentation may be found on the chisel3 repo wiki and the documentation section of the website.


If you wish to submit pull requests for changes to this repo, plus check out the master branch, and make your pull requests against that branch.