Renode, Fomu and EtherBone bridge example

This tutorial shows how to run a hybrid simulation where part of the platform is run in Renode and part on FPGA hardware.

System architecture

The system architecture consists of three main parts:

  • FOMU - Lattice iCE40UP5K-based board with RGB LED, connected to the host machine over USB;
  • EtherBone bridge, translating wishbone packets between TCP and USB;
  • Renode simulating the LiteX platform, running Zephyr OS that controls the RGB LED.

Prerequisites

Simulation

For the simulation part, you need to have the latest version of Renode available in your system.

You can install a prebuilt pacakge for your OS or build a copy from sources as specified in the building instructions.

Hardware

For the hardware part, you need to have the FOMU board.

FOMU needs to be flashed with the Foboot bitstream containing the ValentyUSB IP core with a USB-Wishbone bridge. The manufactured FOMU comes preloaded with this bitstream and can be used right away.

If you have assembled your own copy of the board or changed the original bitsteam, please remember to load Foboot again. For convenience, the prebuilt version of the bitstream is hosted by Antmicro.

EtherBone bridge

In order to connect Renode to FOMU you need to download the EtherBone-to-USB bridge shipped with LiteX.

Clone the repository and initialize the environment:

git clone https://github.com/enjoy-digital/litex
cd litex
./litex_setup.py init  # this will clone the dependencies
export PYTHONPATH=`pwd`:`pwd`/litex:`pwd`/migen

litex_server.py additionally requires the pyusb package to be installed in the system:

pip3 install pyusb

Verifying the device

Plug FOMU into a USB port and verify if it has been recognized by checking the dmesg logs:

[65038.250957] usb 2-1: new full-speed USB device number 16 using xhci_hcd
[65038.409283] usb 2-1: New USB device found, idVendor=1209, idProduct=5bf0, bcdDevice= 1.01
[65038.409286] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[65038.409287] usb 2-1: Product: Fomu DFU Bootloader v1.7.2-3-g9013054
[65038.409288] usb 2-1: Manufacturer: Foosn

Note: The version of the product might differ, but it should work correctly with v.1.7.2 upwards.

If the device is not detected, see the section below.

Loading the bitstream (optional)

If your device is detected as a DFU Bootloader in version 1.7.2 or higher, you can skip this step.

In order to upload a bitstream to a device that is not recognized as a DFU Bootloader you will need an external programming board.

Note

For convenience, you can use the Fomu Programmer - the Open Hardware programming board for FOMU by Antmicro.

Download and make iceprog - open source programming software for Lattice iCE40:

Note

Building iceprog requires the ftdi library headers to be available in the system.

git clone https://github.com/cliffordwolf/icestorm
cd icestorm/iceprog
make

Download the prebuilt bitstream:

wget https://antmicro.com/projects/renode/foboot-bitstream.bin-s_104250-fc5f419372eb9a3a0baa5556483163bcfccb7d33 -O foboot-bitstream.bin

Note

You can also build the bitstream yourself by following the instructions on the Foboot page.

Attach the board to the programmer and load the bitstream to the FPGA:

sudo iceprog foboot-bitstream.bin

Running the demo

Start the EtherBone bridge from the LiteX repository:

cd litex
sudo python3 litex/tools/litex_server.py --usb --usb-vid 0x1209 --usb-pid 0x5bf0

Run the Zephyr OS image in simulation using the script shipped with Renode:

(monitor) start @scripts/complex/fomu/renode_etherbone_fomu.resc

Now you can control the HW LED from Zephyr’s shell using special commands:

uart:~$ led_toggle
uart:~$ led_breathe
led_toggle
toggles the green led
led_breathe
makes the blue led blink with a fade-in/fade-out effect