Build the cross-compiler, various tools, and the base root filesystem for creating embedded firmware images from Erlang/OTP releases. This project uses Buildroot to do all of the hard work. It just provides a configuration and a few helper scripts and patches to customize Buildroot for Erlang/OTP embedded projects.
Currently, the BeagleBone Black is the only supported platform. This
can be changed by adding new configurations to the configs directory and
referencing them from the Makefile.
Before building the SDK, it is important to have a few build tools already installed. Buildroot provides a lot, but it does depend on a few host programs. If using Ubuntu, run the following:
sudo apt-get install git g++ libssl-dev bc
# If your system is 64-bit, also run this
sudo apt-get install libc6:i386 libstdc++6:i386 zlib1g:i386 gcc-multilib
From there, change to the nerves-sdk directory and run:
make
The first time build takes a while since it has to download and
build lot of code. For the most part, you will not need to rebuild
the SDK unless you require a library or other application that
cannot be pulled in by rebar.
In order to use the cross-compiler and the version of Erlang built by Buildroot, you'll need to source a shell script to update various environment settings.
source ./nerves-env.sh
This step has to be done each time you launch a shell. If you use
the SDK regularly, it may be convenient to add this to your .bashrc.
The key environment settings updated by the script are the PATH
variable and a set of variables that direct rebar to invoke the
cross-compiler.
If it turns out that you need another library or application on
your target that can't be pulled in with rebar, you'll need
to update the Buildroot configuration. Luckily, Buildroot comes
with recipes for cross-compiling tons of packages. To change the
configuration, first run the Buildroot configuration utility from
the nerves-sdk directory:
make menuconfig
You'll probably be interested in the "Package Selection for the target"
menu option. After you're done, run make to rebuild the SDK. If you
want to save your set of options permanently, you'll need to copy
buildroot/defconfig to the configs directory.
Be aware that Buildroot caches the root filesystem between builds and that when you unselect a configuration option, it will not disappear from the Nerves SDK root file system image until a clean build.
Nerves comes with several configurations out of the box. These can be used directly or just as an examples for your own custom configuration.
This is the default configuration for building images on the Beaglebone Black. It is a minimal image intended for applications that do not require a lot of hardware or C library support.
This configuration produces a Linux image. It is not useful for Erlang development, but it can be helpful when getting unfamiliar hardware to work. I use it to debug Linux kernel issues since most documentation and developers expect a traditional shell-based environment.
This is the configuration that I'm using for my camera project. Normally it wouldn't be a part of the Nerves SDK, but it may be useful to others as an example. It requires a custom cape for the BeagleBone Black and uses the AM3359's PRU for the hard real-time parts of the project. Erlang is used for the rest.
This configuration is a work-in-progress to support wifi within the Nerves environment. It is currently setup to support a Rosewill RNX-N150UBE (Realtek rtl8712 driver). To test, try run the following programs:
modprobe musb_dsps
ip link set wlan0 up
iwlist wlan0 scan
[use wpa_passphrase to generate a configuration for the wpa_supplicant]
wpa_supplicant -i wlan0 -c /tmp/wifi.conf
ip addr add 192.168.1.40/24 dev wlan0