Quickstart

The environment variable $REPO_TOP is the top-level of the git source tree.

Simulation with Verilator

Make sure you followed the install instructions to prepare the system and to install the software development tools and Verilator.

Build the simulator and the software and then run the simulation

$ cd $REPO_TOP
$ fusesoc --cores-root . run --target=sim --setup --build lowrisc:systems:top_earlgrey_verilator
$ make SIM=1 -C sw/device/boot_rom clean all
$ make SIM=1 -C sw/device/examples/hello_world clean all
$ build/lowrisc_systems_top_earlgrey_verilator_0.1/sim-verilator/Vtop_earlgrey_verilator --rominit=sw/device/boot_rom/rom.vmem \
$ --flashinit=sw/device/examples/hello_world/sw.vmem

See the Getting Started with Verilator Guide for more information.

Running on an FPGA

Make sure you followed the install instructions to prepare the system and to install the software development tools.

Do you want to try out the design without installing EDA tools and waiting for a long build? Then you have come to the right place!

You need the following things:

• A Nexys Video FPGA board (Unfortunately we do not provide presynthesized bitstreams for other FPGA boards right now.)
• A USB pen drive or a microSD card (TODO: specify minimum size)

Once you have obtained these things, follow these steps to get started.

1. Download a release bitstream from the OpenTitan Github Releases page.
2. Connect the Nexys Video board to your PC over USB. TODO: Give good instructions on permission problems/udev rules.
3. Follow the instructions in Section 2.3 of NexysVideo reference manual to prepare the MicroSD card or the USB pen drive, and to configure the FPGA with this bitstream.
4. TODO: include steps on how to build software, spiflash it, and expectations on what should be seen on the board when the software works.

See the Getting Started on FPGAs Guide for full instructions how to build your own bitstream.