Dependencies

Our toolchain is mostly based around Make, so you will want to have it installed. For now, the only exception to this is if you wish to program it to the FPGA, in which case you should use the Gowin IDE directly on Windows or Linux

Firmware

For compiling the firmware from c code you will need to have the risc-v toolchain installed. For MacOS you cand find instructions here, though please note I couldn't install it on MacOS Monterey and updated to MacOS Ventura, in which case it installs from precompilled binaries.

If you wish to compile the firmaware from asm code, we use the python package bronzebeard. We install it as a step in our toolchain, so just make sure you have a venv compatible python installation.

Running

For running the project in the FPGA, just run it on the Gowin IDE. If you wish to update the firmware code, run make compile-firmware to generate the hex file. You can specify a file inside the firmware folder using the optional parameter TARGET_SOURCE which defaults to main.c. For example:

make compile-firmware TARGET_SOURCE=main.asm

Testing

We use verilator as our testbench tool and visualize the results using GTKWave. To run the simulation, simply execute make test. You can also specify a verilog unit file to test with the optional parameter T which defaults to CPU.v. Most of the cases you will want to use the default value.

After runnning the simulation, it will output the waveform to output/VCPU.vcd. You can run GTKWave from the command line with gtkwave output/VCPU.vcd and simply refresh it after running the simulation.

So a normal development flow looks like this:

gtkwave output/VCPU.vcd # In another shell to keep the visualization open

make test
# ... Refresh the view on gtkwave
# change code
make test
# ... Refresh the view on gtkwave