RTEMS for Beagle Bone Black

Table of Contents

• Overview
• Organization
• Building
  • Toolchain and Libraries
  • Application
• Boot process
  • Using the U-Boot from Linux
  • Using a self-made U-Boot

Overview

This repository contains everything that is necessary to run an RTEMS application on the Beagle Bone Black. It includes the libbsd for USB, SD and WiFi support.

Currently supported WiFi adapters are the RT8188EU and RT8188CUS based ones.

Building was tested on Arch GNU/Linux and OpenSUSE GNU/Linux.

This repository is heavily based on the build scripts for GRiSP - a project that runs a Erlang VM on RTEMS. See the grisp-software repository for the original scripts.

Note that a lot of hardware support for the Beagle Bone Black has been done during GSoC. A lot of thanks to the students offering their time for RTEMS. Related projects from the last years are the one from Punit Vara (GSoC 2016) and Sichen Zhao (GSoC2017).

Organization

This repository is organized as follows:

• apps: Various RTEMS applications.

• build: Scripts that help building RTEMS and all tools.

• Datasheets: Datasheets that are used during development.

• debug: Scripts to start a debugger. Currently only Segger is supported.

• libs: Libraries like RTEMS or libbsd.

• tools: Tools and other stuff that is generally useful (for example for generating a SD card image)

• install (generated): All tools and libraries will be installed in this folder.

Building

Toolchain and Libraries

To build all necessary tools and libraries just call ./build/build.sh. This will install all that is necessary to build an application into the install folder.

Note that if you have problems building U-Boot and there are errors of redefinitions of a lot of *fdt* symbols, you most likely have a problem that some system include files collide with the ones expected by U-Boot. I had to uninstall my system dtc to solve that issue.

Application

After building the toolchain, you can build the WiFi sample application. To do that, change into the apps/wifi-sample directory and call make.

You’ll get a b-beagleboneblack/wifi-sample_sdcard.img that can be written to a SD-Card using dd or some similar tool. Mount the SD card on your computer and create a wpa_supplicant.conf in the root directory of the SD. An example can be found in wifi-sample/wpa_supplicant.conf.

After that you can just put the SD-Card into a BBB (with recent U-Boot), connect a RT8188EU based USB WiFi dongle and boot the system. There will be a shell on the serial port of the BBB. After the connection is established (take a look whether you got an IP via DHCP with ifconfig) you can start an ftp-server using the startftp command and do some file transfers.

Boot process

There are multiple possible boot methods

Using the U-Boot from Linux

If you flashed a recent (> about 2017) version of the official Debian Linux image your board will have an U-Boot in the eMMC that reads the uEnv.txt from the SD card (if available) and execute the commands from it. The image generated by build/create-sdcardimage.sh contains all necessary files for that. You can also copy the files to any other FAT formatted SD card in that case.

Using a self-made U-Boot

Alternatively you can use the U-Boot build by build/build-u-boot.sh. Again: Everything that is necessary is already on the image generated by build/create-sdcardimage.sh. To use that U-Boot either press the "S2" button of the BBB during power up or erase the eMMC. In both cases the SD card will be used for boot.