RTEMS Examples

This is a set of example RTEMS programs. Each subdirectory reflects a set of related examples.

Directory	Description
benchmarks	Collection of various public benchmark program
classic_api	Classic API examples (no LED)
cxx	C++ examples
file_io	File I/O
filesystem	File systems, check inside for more details
gdb	Programs to exercise GDB features
hello	Hello World Variations
led	LED Blinker Varations
lvgl_hello	LittleVGL graphics app example using libbsd framebuffer
micromonitor	MicroMonitor interaction examples
misc	Miscellaneous
posix_api	POSIX API examples (no led)
schedsim	RTEMS Scheduler Simulator examples
ticker	Ticker Variations
uboot	U-Boot interaction examples

RTEMS Waf

You can find the Waf project here:

• https://waf.io

Simple instructions on How to set up Waf is here:

• http://www.rtems.org/ftp/pub/rtems/people/chrisj/rtl/rtems-linker/waf.html

Steps

1. Build or install the tools. In this example the path is $HOME/Development/rtems/5.

2. Build and install the RTEMS Board Support Packages you want to use. In this example the path is $HOME/Development/rtems/build/5.

3. Unpack this package somewhere, anywhere on your disk and change into the top level directory.

4. Populate the git submodule:

   $ git submodule init
   $ git submodule update

5. Configure with your specific settings. In this case the path to the tools and RTEMS and provided on the command line and so do not need to be in your path or environment ¹ and we limit the build to a single BSP. The single BSP should be the sparc/erc32 BSP since this is the easiest BSP to use on a simulator. After you have successfully build the executables for this BSP and run them on the simulator, you can repeat this exercise with the BSP you are most interested in.

   $ waf configure --rtems=$HOME/Development/rtems/build/5 \
                   --rtems-tools=$HOME/Development/rtems/5 \
                   --rtems-bsps=sparc/erc32

   You can use these to build more than one BSP at a time:

   $ waf configure --rtems-archs=sparc,i386
   $ waf configure --rtems-bsps=sparc/erc32,i386/pc586

6. Build:

   $ waf

7. Run the executable using the simulator

    $ $HOME/Development/rtems/5/bin/sparc-rtems5-run \
      ./build/sparc-rtems5-erc32/hello

Makefile

The Makefile system used in these examples is dependent on the environment variable RTEMS_MAKEFILE_PATH being set. This can be set on each command line that invokes "make" or it can be exported into your environment.

RTEMS_MAKEFILE_PATH points to the installed BSP image you are compiling for. It is composed as follows:

@prefix@/@target@/BSP

where:

• Prefix is the BSP install point or prefix
• Target is the tool target (e.g. sparc-rtems5)
• BSP is the BSP you are building for (e.g. erc32)

A coupte of examples:

export RTEMS_MAKEFILE_PATH=${HOME}/rtems-work/tools/5/sparc-rtems5/erc32
make clean
make

OR:

RTEMS_MAKEFILE_PATH=${HOME}/rtems-work/tools/5/sparc-rtems5/erc32 make clean
RTEMS_MAKEFILE_PATH=${HOME}/rtems-work/tools/5/sparc-rtems5/erc32 make

You can switch a build from one BSP to another by changing the value of RTEMS_MAKEFILE_PATH but be careful to "make clean" on the old BSP before building the new one.

Deprecration Warning: This style of Makefile has been included in RTEMS since the earliest days. However, it is being replaced by the use of waf and something akin to pkgconfig to obtain compilation settings. The intent is to make it easier for users to configure their preferred build system for an RTEMS application.

Footnotes

1. It is good practice to keep your environment as empty as possible. Setting paths to tools or specific values to configure or control builds is dangerous because settings can leak between different builds and change what you expect a build to do. The waf tool used here lets you specify on the command line the tools and RTEMS paths and this is embedded in waf's configuration information. If you have a few source trees working at any one time with different tool sets or configurations you can easly move between them safe in the knowledge that one build will not infect another. ↩