sweetRV 🧁

This is a fork of femtorv, which is directly ported to work on IceSugar-nano FPGA boards. Kudos to the original authors.

Summary

This repository contains an RISC-V processor that can be packed within 1200LUTs with the RV32I tool chain. There are a bunch of firmware examples to try. You can use the Docker environment directly without installing any dependencies.

Get Started

Docker Image

Follow the steps to build using the Docker environment. (You should have the Docker daemon installed on your system)

1. Clone the repository

git clone https://github.com/Archfx/sweetRV

2. Pull the Docker image from docker-hub

docker pull archfx/ice40tools

3. Set the expected location to mount with the container

export LOC=/sweetRV

4. Run the Docker image

docker run -t -p 6080:6080 -v "${PWD}/:/$LOC" -w /$LOC --name ice40tools archfx/ice40tools

5. Connect to the docker image

docker exec -it ice40tools /bin/bash

Build the hex file generating tool

g++ -I../../LIBFEMTORV32/ ../../LIBFEMTORV32/femto_elf.c firmware_words.cpp -o firmware_words -fpermissive -DSTANDALONE_FEMTOELF

Build the Binary

Now the environment is ready. Next, we need to compile the firmware. This step will take the assembly files/ C source files and generate a hex file that is the firmware for our processor.

$ cd FIRMWARE/EXAMPLES
$ make hello.hex

This will generate the hex file of the firmware. Next, we need to build the hardware with in-built firmware. For that, follow the steps below from the main folder.

$ make ICESUGAR_NANO

This will produce the file femtosoc.bin in the home folder. You can directly upload this to the FPGA by drag and drop.

Terminal of RV32

Firmware contains different example applications that you can run on your FPGA. In order to talk with the processor using UART, you need to install a terminal emulator application (screen/picocom).

Below are the steps for the screen terminal to talk with your processor. Use command + a + \ to exit.

• on Mac

brew  install screen 

/opt/homebrew/Cellar/screen/4.9.0_1/bin/screen /dev/tty.usbmodem102 115200

• on Ubuntu

apt-get install screen 

screen /dev/ttyUSB1 115200