| name | elodin-aleph |
| description | Deploy and configure AlephOS on flight computers, write flight software services, and manage NixOS modules for the Aleph platform. Use when working with aleph/, deploying to Jetson Orin hardware, writing NixOS modules, flashing firmware, or composing a flight software stack. |
Elodin Aleph
Aleph is an NVIDIA Jetson Orin-based flight computer running NixOS. The aleph/ directory contains NixOS modules, packages, and deployment tooling for composing a Linux flight software stack.
Quick Reference
ssh root@fde1:2240:a1ef::1
ssh aleph-99a2.local
./deploy.sh
./deploy.sh root@aleph-99a2.local
nix build --accept-flake-config .#packages.aarch64-linux.sdimage
Initial Setup
- Connect USB-C to rightmost port on Aleph
ssh root@fde1:2240:a1ef::1 (password: root)- Follow
aleph-setup wizard (or run it manually)
- Connect to WiFi:
iwctl station wlan0 connect "NetworkName"
- Verify:
ping google.com
After WiFi setup, SSH directly via aleph-XXXX.local.
Development Workflow
The recommended cycle for iterating on the NixOS configuration:
- Edit files in
aleph/flake.nix, aleph/modules/, or aleph/kernel/
- Run
./deploy.sh from the aleph/ directory
- The script builds, copies store paths, and activates the new config
- To revert: reboot and select previous bootloader entry (requires serial console on left USB-C port)
NixOS Module System
Configuration is in aleph/flake.nix, composed from modules in aleph/modules/:
Hardware & Base
| Module | Purpose |
|---|
hardware.nix | Forked kernel, device tree for Orin |
fs.nix | SD-card image compatibility |
usb-eth.nix | USB Ethernet gadget (IPv6 fde1:2240:a1ef::1) |
wifi.nix | WiFi via iwd |
minimal.nix | Minimal NixOS profile |
aleph-base.nix | Base configuration |
aleph-dev.nix | Dev packages (CUDA, OpenCV, git) |
Flight Software Services
| Module | Purpose |
|---|
c-blinky.nix | STM32 firmware flash-on-deploy + serial-bridge ordering |
elodin-db.nix | Elodin-DB telemetry database service |
aleph-serial-bridge.nix | Sensor data from serial โ Elodin-DB |
mekf.nix | MEKF attitude estimation service |
msp-osd.nix | MSP DisplayPort OSD for FPV goggles |
udp-component-broadcast.nix | UDP component broadcasting |
udp-component-receive.nix | UDP component receiving |
elodinsink.nix | GStreamer plugin for video โ Elodin-DB |
tegrastats-bridge.nix | Orin SoC telemetry bridge |
Setup & Status
| Module | Purpose |
|---|
aleph-setup.nix | First-time setup wizard |
installer.nix | USB installer system |
Template flake.nix
aleph/template/flake.nix is the starting point for user configurations. It imports Aleph modules and configures services:
# Key structure in template/flake.nix
{
inputs.elodin.url = "github:elodin-sys/elodin";
outputs = { self, elodin, nixpkgs }: {
nixosConfigurations.aleph = nixpkgs.lib.nixosSystem {
modules = [
elodin.nixosModules.aleph-base
elodin.nixosModules.elodin-db
elodin.nixosModules.mekf
# ... other modules
];
};
};
}
Available FSW Applications
These Rust applications in fsw/ run as NixOS services on Aleph:
| Application | Path | Purpose |
|---|
c-blinky | fsw/c-blinky/ | STM32H747 bare-metal LED blink + UART COBS logging |
sensor-fw | fsw/sensor-fw/ | STM32H747 firmware: IMU, mag, baro โ USB/UART |
serial-bridge | fsw/serial-bridge/ | Serial port โ Elodin-DB (parses EL COBS frames) |
mekf | fsw/mekf/ | Sensor fusion for attitude estimation |
msp-osd | fsw/msp-osd/ | OSD telemetry display for FPV |
gstreamer | fsw/gstreamer/ | H.264 video โ Elodin-DB (elodinsink) |
video-streamer | fsw/video-streamer/ | Video files โ AV1 โ Elodin-DB |
udp_component_broadcast | fsw/udp_component_broadcast/ | Real-time UDP component sharing |
aleph-status | fsw/aleph-status/ | System status display |
aleph-setup | fsw/aleph-setup/ | Interactive first-time setup |
blackbox | fsw/blackbox/ | Blackbox data processing |
lqr | fsw/lqr/ | LQR control system |
Fresh Install / Recovery
For unbootable or corrupted systems:
- Build SD image:
nix build --accept-flake-config .#packages.aarch64-linux.sdimage
- Flash to USB:
sudo dd if=aleph-os.img of=/dev/sdX bs=4M status=progress oflag=sync
- Boot from middle USB-C port
- SSH via rightmost USB-C:
ssh root@fde1:2240:a1ef::1
- Run
aleph-installer
- Remove USB and reboot
MCU Operations
reset-mcu --app
reset-mcu --bootloader
reset-mcu --nrst-low
reset-mcu --nrst-high
reset-mcu --boot0-high
flash-mcu --bin firmware.bin
flash-mcu --elf firmware.elf
STM32H747 UART Flashing
The STM32 is flashed from the Orin via the ROM UART bootloader using stm32flash at 19200 8E1 on /dev/ttyTHS1. The NixOS service c-blinky-flash handles this automatically during deploy.sh.
Critical timing requirement: The STM32H747 ROM bootloader has a narrow interface detection window (~100ms) after NRST release. The stm32flash 0x7F sync byte must arrive during this window. If missed, the ROM falls to a dual-core sync handler and hangs forever. The flash-mcu.sh UART path handles this with tight timing: NRST low -> BOOT0 high -> NRST release -> 100ms -> stm32flash.
Tegra UART quirk: stm32flash cannot set termios flags on ttyTHS* devices. The script pre-configures the port with stty before calling stm32flash.
GPIO mapping (open-source expansion board):
- BOOT0: gpiochip0 line 144 (B2B pin 33)
- NRST: gpiochip0 line 106 (B2B pin 36)
STM32 Firmware (c-blinky)
fsw/c-blinky/main.c is bare-metal C for the STM32H747 CM7 core. Runs on HSI at 64MHz (no PLL). Outputs COBS-encoded EL log frames on USART1 PA9 (TX) at 115200 8N1. The serial-bridge service parses these frames and forwards them to elodin-db as aleph.stm32.log.
EL frame wire format: 0x00 | COBS(['E','L', ver=1, kind=1, level, ...msg...]) | 0x00
Built by Nix (aleph/pkgs/c-blinky.nix) using arm-none-eabi-gcc. Produces firmware.elf and firmware.bin.
Elodin-DB on Aleph
The elodin-db.nix module defaults to dbUniqueOnBoot = true, creating a fresh timestamped elodin-db instance on each deploy/boot at /db/default-YYYYMMDD-HHMMSS on port 2240. The elodin-db-default oneshot manages the lifecycle: it stops any old elodin-db@* template instances and waits for port 2240 to be free before starting the new one. The template service has stopIfChanged = false; restartIfChanged = false so NixOS activation never races with it. Set dbUniqueOnBoot = false for a single persistent /db/default instance.
Each fresh database ingests the shared asset root (services.elodin-db.assetsDir, default /var/lib/elodin/assets โ the ELODIN_ASSETS tree seeded by the elodin module) via elodin-db run --assets, so a HITL recording carries its schematic assets under {db}/assets/ and is a complete, portable record: copy the /db/default-* directory off the vehicle and serve it anywhere with elodin-db run. Set assetsDir = null to disable ingest.
Connect from a development machine: elodin editor <aleph-ip>:2240
For SITL work against the same flight stack, examples/betaflight-sitl/ is the reference SITL example (Betaflight lockstep over UDP, recorded to a portable DB).
Key References
