OpenRAM

An open-source static random access memory (SRAM) compiler.

This project is maintained by VLSIDA

OpenRAM

Python 3.5 License: BSD 3-clause Download Download

An open-source static random access memory (SRAM) compiler.

What is OpenRAM?

OpenRAM is an award winning open-source Python framework to create the layout, netlists, timing and power models, placement and routing models, and other views necessary to use SRAMs in ASIC design. OpenRAM supports integration in both commercial and open-source flows with both predictive and fabricable technologies.

Documentation

Please take a look at our presentation We have created a detailed presentation that serves as our documentation. This is the most up-to-date information, so please let us know if you see things that need to be fixed.

Basic Setup

Dependencies

Please see the Dockerfile for the required versions of tools.

In general, the OpenRAM compiler has very few dependencies:

Docker

We have a docker setup to run OpenRAM. To use this, you should run:

cd openram/docker
make build

This must be run once and will take a while to build all the tools.

Environment

You must set two environment variables:

For example add this to your .bashrc:

  export OPENRAM_HOME="$HOME/openram/compiler"
  export OPENRAM_TECH="$HOME/openram/technology"

You should also add OPENRAM_HOME to your PYTHONPATH:

  export PYTHONPATH=$OPENRAM_HOME

Note that if you want symbols to resolve in your editor, you may also want to add the specific technology directory that you use and any custom technology modules as well. For example:

  export PYTHONPATH="$OPENRAM_HOME:$OPENRAM_TECH/sky130:$OPENRAM_TECH/sky130/custom"

We include the tech files necessary for SCMOS SCN4M_SUBM, FreePDK45. The SCMOS spice models, however, are generic and should be replaced with foundry models. You may get the entire FreePDK45 PDK here.

Sky130 Setup

To install Sky130, you must have the open_pdks files installed in $PDK_ROOT. To install this automatically, you can run:

cd $HOME/openram make pdk

Then you must also install the Sky130 SRAM build space and the appropriate cell views by running:

cd $HOME/openram make install

Basic Usage

Once you have defined the environment, you can run OpenRAM from the command line using a single configuration file written in Python.

For example, create a file called myconfig.py specifying the following parameters for your memory:

# Data word size
word_size = 2
# Number of words in the memory
num_words = 16

# Technology to use in $OPENRAM_TECH
tech_name = "scn4m_subm"

# You can use the technology nominal corner only
nominal_corner_only = True
# Or you can specify particular corners
# Process corners to characterize
# process_corners = ["SS", "TT", "FF"]
# Voltage corners to characterize
# supply_voltages = [ 3.0, 3.3, 3.5 ]
# Temperature corners to characterize
# temperatures = [ 0, 25 100]

# Output directory for the results
output_path = "temp"
# Output file base name
output_name = "sram_{0}_{1}_{2}".format(word_size,num_words,tech_name)

# Disable analytical models for full characterization (WARNING: slow!)
# analytical_delay = False

You can then run OpenRAM by executing:

python3 $OPENRAM_HOME/openram.py myconfig

You can see all of the options for the configuration file in $OPENRAM_HOME/options.py

To run designs in Docker, it is suggested to use, for example:

cd openram/macros
make example_config_scn4m_subm

Unit Tests

Regression testing performs a number of tests for all modules in OpenRAM. From the unit test directory ($OPENRAM_HOME/tests), use the following command to run all regression tests:

cd openram/compiler/tests
make -j 3

The -j can run with 3 threads. By default, this will run in all technologies.

To run a specific test in all technologies:

cd openram/compiler/tests
make 05_bitcell_array_test

To run a specific technology:

cd openram/compiler/tests
TECHS=scn4m_subm make 05_bitcell_array_test

To increase the verbosity of the test, add one (or more) -v options and pass it as an argument to OpenRAM:

ARGS="-v" make 05_bitcell_array_test

Unit test results are put in a directory:

openram/compiler/tests/results/<technology>/<test>

If the test fails, there will be a tmp directory with intermediate results. If the test passes, this directory will be deleted to save space. You can view the .out file to see what the output of a test is in either case.

Get Involved

Further Help

License

OpenRAM is licensed under the BSD 3-clause License.

Contributors & Acknowledgment

If I forgot to add you, please let me know!