AUxspace Real-time Onboard Rocket Avionics

This is the project's info page. For detailed documentation head to aurora.auxspace.de.

• RTOS: Real-Time Operating System
• µC: MicroController (µ - Controller)
• MCU: MicroController Unit
• SOC: System On Chip
• Zephyr: Open-Source RTOS Kernel for a large variety of MCUs and SOCs (https://www.zephyrproject.org/)
• fork: A forked repository is a direct clone of another, with custom modifications made
• Docker: "Docker Engine is an open source containerization technology for building and containerizing your applications" (https://docs.docker.com/engine/)
• devicetree: Tree-like configuration for hardware integration (https://docs.kernel.org/devicetree/index.html)

AURORA is an open-source software project developed by Auxspace e.V., a student-driven initiative dedicated to building rockets and providing hands-on aerospace engineering experience. This project is specifically designed for the Auxspace e.V. Rocket Electronics Stack, incorporating a modular electronics stack for optimal performance and flexibility.

The AURORA system leverages a series of interconnected PCBs communicating over CAN, with each PCB housing a microchip running either the AURORA software or adding value to it (e.g. GPIO port expanders, pyro ignition channels or long-range communication modules). The primary purpose of AURORA is to serve as avionics software, managing essential data such as air pressure, acceleration, gyro, and magnetometer readings in a plug-and-play state machine with configurable filters and events. Using the zephyr kernel, AURORA handles task scheduling and real-time operations, enabling reliable and efficient communication between multiple AURORA instances through CAN.

Join us as we continue to develop and refine AURORA, contributing to the advancement of rocket technology and student expertise in aerospace engineering!

Setup zephyr using either the docker container in this directory or follow the Getting Started Guide from the Zephyr project.

First, create a workspace:

mkdir zephyr_workspace && cd zephyr_workspace

Then, install the system dependencies:

x86 Debian Linux:

sudo apt install --no-install-recommends git cmake ninja-build gperf \
  ccache dfu-util device-tree-compiler wget python3-dev python3-venv python3-tk \
  xz-utils file make gcc libsdl2-dev libmagic1

# x86 specific
sudo apt-get install -y --no-install-recommends \
    gcc-multilib g++-multilib

or if you are on fedora:

sudo dnf install -y \
    git cmake ninja-build gperf \
    ccache dfu-util dtc wget python3-devel python3-virtualenv python3-tkinter \
    xz file make gcc gcc-c++ glibc-devel.i686 libstdc++-devel.i686 \
    SDL2-devel file-libs

Using a python virtualenv, install west, zephyr's pythondependencies and the zephyr sdk with the required toolchains:

python3 -m venv .venv
source .venv/bin/activate

python3 -m pip install west

west init -m https://github.com/AUXSPACEeV/aurora --mr main .
cd aurora
west update
west zephyr-export
west packages pip --install

west sdk install -t \
    riscv64-zephyr-elf \
    arm-zephyr-eabi \
    xtensa-espressif_esp32s3_zephyr-elf \
    x86_64-zephyr-elf

This should leave a directory setup like so:

zephyr_workspace
├── aurora
├── modules
├── .venv
├── .west
└── zephyr

mkdir zephyr_workspace
cd zephyr_workspace
git clone -b main https://github.com/AUXSPACEeV/aurora.git aurora
cd aurora

# Open a shell in the development container for the sensor_board_v2/rp2040 board
./run.sh -b sensor_board_v2/rp2040 shell

zephyr_workspace
├── aurora
├── modules
├── .west
└── zephyr

The important directories in this project are

1. <zephyr_workspace>
2. <aurora>

If you ran west init -m https://github.com/AUXSPACEeV/aurora --mr main . in ~/zephyr_workspace then <aurora> will be at ~/zephyr_workspace/aurora.

The following commands are examples of how to use west when building an application. Start the command from the <aurora> dir:

# Build the sensor_board project for the sensor_board_v2/rp2040
west build -b sensor_board_v2/rp2040 sensor_board

# Another example: build for the custom Auxspace Micrometer PCB:
west build -b micrometer/esp32s3/procpu --sysbuild sensor_board/

The output from the build will be at <aurora>/build/zephyr, called zephyr.uf2 and zephyr.elf.

note: This chapter shows how to deploy AURORA onto the sensor_board_v2 as an example. The board uses a Raspberry Pi Pico Series microcontroller as its main logic unit.

Deploy the binary to your board by either using west flash or the Board manufacturers' manual. In case of the sensor_board_v2 that would be Raspberry Pi.

note: flashing from inside the docker container is currently untested and unimplemented.

The following is an example on how to flash AURORA onto the Pi using openocd:

# Flash the PI
sudo openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -c "adapter speed 5000" -c "program build/zephyr/zephyr.elf verify reset exit"

# Attach to debug probe
sudo openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -c "adapter speed 5000"

# Connect gdb to openocd
gdb build/zephyr/zephyr.elf
>target remote localhost:3333
>monitor reset init

# Start debugging!

The RP2040 and RP2350 come with a backup bootloader, in case the QSPI Flash is not responding to the ROM bootloader. The BOOTSEL switch deasserts the QSPI Chip Select pin and opens up the fallback loader, which is a simple USB interface. When connecting the PI to your PC in this state, the PI is registered as an external drive called RPI-RP2, which can load .uf2 files by simply copying these firmware files onto the drive.

Copy the files from your drive to the Pi's filesystem like so, or with your file explorer:

# Linux example
cp build/zephyr/zephyr.uf2 /media/${USER}/RPI-RP2

# MACOS example
cp build/zephyr/zephyr.uf2 /Volumes/RPI-RP2

The PI should reboot and immediately start running your uploaded application.

Zephyr provides a testing environment called twister. This repo adds twister compliant testcases under tests/:

# In docker:
west twister -T tests -v --inline-logs

note: Make sure to install the necessary toolchain for a given test! e.g. the basic tests require x86_64-zephyr-elf:

west sdk install -t x86_64-zephyr-elf