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https://github.com/cocotb/cocotb
cocotb, a coroutine based cosimulation library for writing VHDL and Verilog testbenches in Python
https://github.com/cocotb/cocotb
python test uvm verification verilog vhdl
Last synced: 3 days ago
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cocotb, a coroutine based cosimulation library for writing VHDL and Verilog testbenches in Python
- Host: GitHub
- URL: https://github.com/cocotb/cocotb
- Owner: cocotb
- License: bsd-3-clause
- Created: 2013-06-12T20:07:15.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2024-10-29T08:47:29.000Z (about 1 month ago)
- Last Synced: 2024-10-29T09:58:40.630Z (about 1 month ago)
- Topics: python, test, uvm, verification, verilog, vhdl
- Language: Python
- Homepage: https://www.cocotb.org
- Size: 8.22 MB
- Stars: 1,794
- Watchers: 108
- Forks: 511
- Open Issues: 443
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
- awesome-opensource-hardware - cocotb
- awesome-open-hardware-verification - Cocotb
- awesome-hwd-tools - cocotb/cocotb - Creating Verilog/VHDL testbenches with python (Semi Custom Design/ FPGAs / Verification)
README
**cocotb** is a coroutine based cosimulation library for writing VHDL and Verilog testbenches in Python.
[](https://docs.cocotb.org/en/latest/)
[](https://github.com/cocotb/cocotb/actions/workflows/build-test-dev.yml)
[](https://pypi.org/project/cocotb/)
[](https://gitpod.io/#https://github.com/cocotb/cocotb)
[](https://codecov.io/gh/cocotb/cocotb)
* Read the [documentation](https://docs.cocotb.org)
* Get involved:
* [Raise a bug / request an enhancement](https://github.com/cocotb/cocotb/issues/new) (Requires a GitHub account)
* [Join the Gitter chat room](https://gitter.im/cocotb/Lobby)
**Note: The current `master` branch of the cocotb repository is expected to be released as cocotb 2.0, which contains API-breaking changes from previous 1.x releases. Please use the `stable/1.9` branch if you're building cocotb from source, or just [install it from PyPi](https://pypi.org/project/cocotb/).**
## Installation
The current stable version of cocotb requires:
- Python 3.6+
- GNU Make 3+
- An HDL simulator (such as [Icarus Verilog](https://docs.cocotb.org/en/stable/simulator_support.html#icarus-verilog),
[Verilator](https://docs.cocotb.org/en/stable/simulator_support.html#verilator),
[GHDL](https://docs.cocotb.org/en/stable/simulator_support.html#ghdl) or
[other simulator](https://docs.cocotb.org/en/stable/simulator_support.html))
After installing these dependencies, the latest stable version of cocotb can be installed with pip.
```command
pip install cocotb
```
For more details on installation, including prerequisites,
see [the documentation](https://docs.cocotb.org/en/stable/install.html).
For details on how to install the *development* version of cocotb,
see [the preliminary documentation of the future release](https://docs.cocotb.org/en/latest/install_devel.html#install-devel).
## Usage
As a first trivial introduction to cocotb, the following example "tests" a flip-flop.
First, we need a hardware design which we can test. For this example, create a file `dff.sv` with SystemVerilog code for a simple [D flip-flop](https://en.wikipedia.org/wiki/Flip-flop_(electronics)#D_flip-flop). You could also use any other language a [cocotb-supported simulator](https://docs.cocotb.org/en/stable/simulator_support.html) understands, e.g. VHDL.
```systemverilog
// dff.sv
`timescale 1us/1ns
module dff (
output logic q,
input logic clk, d
);
always @(posedge clk) begin
q <= d;
end
endmodule
```
An example of a simple randomized cocotb testbench:
```python
# test_dff.py
import random
import cocotb
from cocotb.clock import Clock
from cocotb.triggers import RisingEdge
from cocotb.types import LogicArray
@cocotb.test()
async def dff_simple_test(dut):
"""Test that d propagates to q"""
# Assert initial output is unknown
assert LogicArray(dut.q.value) == LogicArray("X")
# Set initial input value to prevent it from floating
dut.d.value = 0
clock = Clock(dut.clk, 10, units="us") # Create a 10us period clock on port clk
# Start the clock. Start it low to avoid issues on the first RisingEdge
cocotb.start_soon(clock.start(start_high=False))
# Synchronize with the clock. This will regisiter the initial `d` value
await RisingEdge(dut.clk)
expected_val = 0 # Matches initial input value
for i in range(10):
val = random.randint(0, 1)
dut.d.value = val # Assign the random value val to the input port d
await RisingEdge(dut.clk)
assert dut.q.value == expected_val, f"output q was incorrect on the {i}th cycle"
expected_val = val # Save random value for next RisingEdge
# Check the final input on the next clock
await RisingEdge(dut.clk)
assert dut.q.value == expected_val, "output q was incorrect on the last cycle"
```
A simple Makefile:
```make
# Makefile
TOPLEVEL_LANG = verilog
VERILOG_SOURCES = $(shell pwd)/dff.sv
TOPLEVEL = dff
MODULE = test_dff
include $(shell cocotb-config --makefiles)/Makefile.sim
```
In order to run the test with Icarus Verilog, execute:
```command
make SIM=icarus
```
[](https://asciinema.org/a/317220)
For more information please see the [cocotb documentation](https://docs.cocotb.org/)
and [our wiki](https://github.com/cocotb/cocotb/wiki).
## Tutorials, examples and related projects
* the tutorial section [in the official documentation](https://docs.cocotb.org/)
* [cocotb-bus](https://github.com/cocotb/cocotb-bus) for pre-packaged testbenching tools and reusable bus interfaces.
* [cocotb-based USB 1.1 test suite](https://github.com/antmicro/usb-test-suite-build) for FPGA IP, with testbenches for a variety of open source USB cores
* [`cocotb-coverage`](https://github.com/mciepluc/cocotb-coverage), an extension for Functional Coverage and Constrained Randomization
* [`uvm-python`](https://github.com/tpoikela/uvm-python), an almost 1:1 port of UVM 1.2 to Python
* [`pyuvm`](https://github.com/pyuvm/pyuvm), The UVM IEEE 1800.2 specification built upon cocotb and implemented from scratch in Python.
* our wiki [on extension modules](https://github.com/cocotb/cocotb/wiki/Further-Resources#extension-modules-cocotbext)
* the list of [GitHub projects depending on cocotb](https://github.com/cocotb/cocotb/network/dependents)