microwatt/esim/README.md

Microwatt eSim Integration

Overview

This directory contains initial integration support for running the OpenPOWER Microwatt core inside the eSim/NGHDL co-simulation environment.

The integration flow enables Microwatt to be compiled with GHDL and wrapped for NGHDL/XSPICE-based simulation inside eSim.

Files

microwatt_cosim.vhdl

NGHDL-compatible wrapper for Microwatt.

Exposed ports:

• clk : Clock input
• rst : Reset input
• uart_tx : UART transmit output

compile_for_nghdl.sh

Build script used to:

• Compile Microwatt using GHDL
• Build required helper objects
• Elaborate the wrapper for NGHDL/XSPICE integration

Build Flow

Run:

bash esim/compile_for_nghdl.sh

Successful compilation generates the NGHDL-compatible elaborated design.

eSim Workflow

1. Compile Microwatt using the provided script

2. Generate the NGHDL/XSPICE codemodel

3. Import the generated block into eSim

4. Create a schematic using:

   • clock pulse
   • reset pulse
   • UART probe

5. Run transient simulation

Current Status

• Wrapper compilation successful
• NGHDL integration validated
• Basic schematic-level simulation setup completed

Future Work

• Add memory and peripheral models
• Expand validation workflows
• Add example system-level designs