# Microwatt A tiny Open POWER ISA softcore written in VHDL 2008. It aims to be simple and easy to understand. ## Simulation using ghdl

You can try out Microwatt/Micropython without hardware by using the ghdl simulator. If you want to build directly for a hardware target board, see below. - Build micropython. If you aren't building on a ppc64le box you will need a cross compiler. If it isn't available on your distro grab the powerpc64le-power8 toolchain from https://toolchains.bootlin.com ``` git clone https://github.com/micropython/micropython.git cd micropython cd ports/powerpc make -j$(nproc) cd ../../../ ``` - Microwatt uses ghdl for simulation. Either install this from your distro or build it. Next build microwatt: ``` git clone https://github.com/antonblanchard/microwatt cd microwatt make ``` - Link in the micropython image: ``` ln -s ../micropython/ports/powerpc/build/firmware.bin main_ram.bin ``` - Now run microwatt, sending debug output to /dev/null: ``` ./core_tb > /dev/null ``` ## Synthesis on Xilinx FPGAs using Vivado - Install Vivado (I'm using the free 2019.1 webpack edition). - Setup Vivado paths: ``` source /opt/Xilinx/Vivado/2019.1/settings64.sh ``` - Install FuseSoC: ``` pip3 install --user -U fusesoc ``` Fedora users can get FuseSoC package via ``` sudo dnf copr enable sharkcz/danny sudo dnf install fusesoc ``` - Create a working directory and point FuseSoC at microwatt: ``` mkdir microwatt-fusesoc cd microwatt-fusesoc fusesoc library add microwatt /path/to/microwatt/ ``` - Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100): ``` fusesoc run --target=nexys_video microwatt --memory_size=8192 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex ``` You should then be able to see output via the serial port of the board (/dev/ttyUSB1, 115200 for example assuming standard clock speeds). There is a know bug where initial output may not be sent - try the reset (not programming button on your board if you don't see anything. - To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200): ``` fusesoc run --target=nexys_video microwatt ``` ## Testing - A simple test suite containing random execution test cases and a couple of micropython test cases can be run with: ``` make -j$(nproc) check ``` ## Issues This is functional, but very simple. We still have quite a lot to do: - There are a few instructions still to be implemented - Need to add caches and bypassing (in progress) - Need to add supervisor state (in progress)