RIOT supports the Qemu and Renode emulation tools. The emulation offers a hardware-free development environment for quickly testing applications.

From the build system point of view, the emulation support in RIOT is transparent compared to the usual workflow: simply add EMULATE=1 to the command line and the emulator supported by the board will be called instead of the board flashing/debugging tool. Targets compatible with EMULATE=1 are term, cleanterm, debug, debugserver and test.

If a board supports multiple emulators, the emulator backend can be selected with the RIOT_EMULATOR variable. Possible values are qemu and renode. If no emulator is specified by the board configuration (e.g. in its Makefile.include), the default emulator is renode.

The boards with emulator supported can be listed using the info-emulated-boards target:

$ make info-emulated-boards

Features

Be aware that not all hardware features provided by a board - and described as such in the build system by FEATURES_PROVIDED - are implemented in emulators. For example, the hifive1b provides the RTC peripheral feature but this is not implemented by the renode driver. So you may expect some failures when running advanced applications on the emulator.

Usage

All emulators can be used the same way. Just add EMULATE=1 to the command line.

To start an emulator and connect to the serial port of the emulated board, run:

$ EMULATE=1 make BOARD=<board> -C <application directory> all term

To start an emulator with a GDB server and connect a GDB client to it, run:

$ EMULATE=1 make BOARD=<board> -C <application directory> all debug

To start an automatic test script with the emulated board, run:

$ EMULATE=1 make BOARD=<board> -C <test application directory> all test

The EMULATOR_SERIAL_PORT variable can be used to specify a custom serial port on the host running the emulator. The default value is built based on a random temporary directory: $(EMULATOR_TMP_DIR)/uart. The randomness of this variable allows several emulated sessions of the same application with the same board to run in parallel.

Qemu

Overview

Qemu is a machine emulator and virtualizer. It can be used to emulate regular computer architectures but also some microcontroller based boards such as the BBC micro:bit.

Installation

Qemu is usually available via the package manager of common Linux distributions. Depending on your local system, the installation procedure is described on the qemu website.

Boards supported

So far, in RIOT, only the BBC micro:bit board is supported with qemu.

Configuration

The QEMU emulated serial port is exposed on a local Unix socket, redirected to a local PTY file (using socat). This makes it possible to open the PTY file in a regular serial port.

Renode

Overview

Renode is a virtual development tool for multinode embedded networks (both wired and wireless) enabling a scalable workflow for building effective, tested and secure IoT systems, created by Antmicro](http://antmicro.com/blog/2017/08/renode-press-release/). It can easily be used to run applications on a broad range of embedded platforms without any changes in the code itself, as if you were running on real hardware - but with more possibilities.

Installation

From package

Packages for macOS, deb-based and rpm-based systems, for Windows and for Arch Linux are available on GitHub.

From source

Follow the installation instructions on Renode's GitHub page.

If you choose to build renode from source, after the compilation is successful, ensure that renode is available on your PATH. One way to do so, is via symlink:

sudo ln -s path/to/renode/repository/renode /usr/local/bin/renode

Testing

After installation, verify that Renode is working using renode --help. You should be presented with a help screen.

Documentation

Documentation for Renode can be found on Read The Docs.

Usage

From within RIOT-OS, add EMULATE=1 to start the emulation. The emulation expects a board definition file in boards/<BOARD>/dist/board.resc.

The board definition file will tell Renode how to setup an emulation session. The application binary file (*.elf) is available using the variable $image_file.

For an example, refer to boards/cc2538dk/dist/board.resc.

The renode logging level can be configured from the command line using the following variables:

RENODE_SHOW_LOG: set it to 1 to show the logs in the standard output
RENODE_LOG_LEVEL: set it to the desired log level, default is 2 (warning)

The renode monitor and serial console GUI windows are hidden by default but they can be displayed by setting RENODE_SHOW_GUI to 1 in the command line.

If uart0 is not the default serial port used for stdio, use RENODE_SYSBUS_UART to specify a custom one in the board Makefile.include.