OpenRISC Tutorials

These are tutorials for the OpenRISC processor. The tutorials run on different FPGA boards and simulators. Hence, the different tutorials have different requirements. Each tutorial tries to be as independent as possible and will instruct you how to download what is needed, but for FPGA development some basics will be needed.

Contributing

If you wish to contribute to the tutorials please see our openrisc/totorials git repo where this site’s source code is hosted.

Checkout the TODO list in README.md.

Programming

These tutorials cover setting up development environments for OpenRISC hardware and/or software development. For embedded system programming we recommend getting familiar with OpenRISC assembly and C.

Assembly

If you are interested in writing programs in OpenRISC assembly read the OpenRISC architecture spec to understand the capabilities and programming model of OpenRISC.

Example of what OpenRISC assembly looks like:

        .global _main
_main:
        l.ori   r3, r0, 2
        l.ori   r4, r0, 2
        l.mul   r5, r3, r4
        l.sfeqi r5, 4
        l.bf    test_ok
         l.nop

Bare Metal C/C++

If you want to write programs in bare metal C taking advantage of the OpenRISC architecture facilities such as exception handling, MMU and timers checkout the newlib or1k apis.

Example of what OpenRISC bare metal looks like:

#include <or1k-support.h>
#include <or1k-sprs.h>
#include <stdint.h>

void
or1k_interrupts_enable(void)
{
        uint32_t sr = or1k_mfspr(OR1K_SPR_SYS_SR_ADDR);
        sr = OR1K_SPR_SYS_SR_IEE_SET(sr, 1);
        or1k_mtspr(OR1K_SPR_SYS_SR_ADDR, sr);
}

uint32_t
or1k_interrupts_disable(void)
{
        uint32_t oldsr, newsr;
        oldsr= or1k_mfspr(OR1K_SPR_SYS_SR_ADDR);
        newsr = OR1K_SPR_SYS_SR_IEE_SET(oldsr, 0);
        or1k_mtspr(OR1K_SPR_SYS_SR_ADDR, newsr);
        return OR1K_SPR_SYS_SR_IEE_GET(oldsr);
}

See the newlib tutorial for details on how to setup the newlib development environment. Or checkout the Quickstart tutorial for docker images that have the newlib environment out of the box.

Tools (partially required)

FuseSoC

FuseSoC is an automated build environment and package manager for OpenRISC. You can install it as described here.

Featured in:

• De0 Nano - De0 Nano FPGA development board platform tutorial.
• Quickstart Images - Docker verilog development environment

OpenOCD

The OpenOCD version delivered with the Linux distributions is most probably outdated. Hence, you can quickly install a current version.

Featured in:

• De0 Nano - De0 Nano FPGA development board platform tutorial.
• Debugging - OpenOCD debugging cheat sheet.

Quartus Prime

This is the software which compiles RTL and ultimately generates an FPGA programming file. Unfortunately this software is closed source, extremely large, and requires registration to download. However, it is required for some tutorials.

Featured in:

• De0 Nano - De0 Nano FPGA development board platform tutorial.

For downloading the free version, visit the Intel website and download the latest version of Quartus Prime Lite. It is more than 7GB in size and will obviously take a while to download. Once it is downloaded, extract it and run the setup.sh file in there. Install it to any location.

Once downloaded and extracted you can run the installer from the command line as follows:

./components/QuartusLiteSetup-24.1std.0.1077-linux.run  --mode text \
  --unattendedmodeui none \
  --installdir /opt/quartus-24.1 \
  --disable-components quartus_help --accept_eula 1

After installation add the following path (corrected for your installation) to the search path:

export PATH=/opt/quartus-24.1/quartus/bin/:$PATH

Note: Make sure you select to include the Cyclone IV E device families during installation.

Vivado

Like Quartus this is the software which compiles RTL and generates an FPGA programming file. This software is closed source, extremely large, and requires registration to download. It is required for the Litex ARTY tutorials.

Visit the Vivado downloads page and get the latest version.