OWL - Rotor v2

OWL Hardware

Hardware design files for the OWL measurement tool.

The OWL is a rotating platform driven by a BLDC motor under field-oriented control. Power and USB data are passed from the stationary base to the rotating part through a slip ring, so devices mounted on top can be rotated continuously while staying connected to a host.

Status

• v1.0.0 is the OWL as built and tested. It works, with the known issues listed in its release notes: the 5V rail can oscillate when USB and the power supply are both connected (workaround: cut the controller's VBUS jumper JP1), the stator's data USB-C port only works in one cable orientation, the sensor's mounting holes are missing (drill them, 1.8 mm), the green LEDs are very bright, and the USB hub (IC1) has no pin-1 marker.
• Releases after v1.0.0, including the latest, should fix these issues, but no boards have been built from them yet, so they are untested. Other changes since the built boards: plated shell-tab holes for the controller's USB-C connector J3, a different part for the controller's USER LED D7, and no assembled parts on the controller's bottom side.
• The payload adapters and the tripod mount in payload/ use version 2 of the payload connector, which is incompatible with version 1. For an OWL with the version 1 connector, use release v1.2.2.
• The 5V oscillation is only worked around: JP1 now ships open, so the controller runs from the power supply only (see Power supply). A proper fix is planned for the next board revision.

Building an OWL

1. Download the files from the latest release:
   • owl-<version>-jlcpcb.zip: everything needed to order the three assembled PCBs from JLCPCB
   • owl-<version>-3d-print.zip: the 3D-printed parts
   • owl-<version>-generic.zip: manufacturer-neutral PCB files and schematics, if you order elsewhere
2. Order the PCBs, see pcb/README.md.
3. Print the parts, see cad/README.md.
4. Assemble the OWL and flash the firmware, see the assembly instructions.
5. Print an adapter for your payload, see payload/README.md.

Architecture

• Stator PCB: Sits in the stationary base. Provides the USB-C power input with a USB PD trigger (CH224K) and the USB data port to the host.
• Rotor PCB (controller): Rotates with the platform. Contains the RP2354B controller, the DRV8311 BLDC driver, 5 V and 3.3 V regulators, a USB hub with a passthrough port for the payload, and a Qwiic (I²C) port.
• Magnetic sensor PCB: Measures the rotor angle for motor control using a magnetic angle sensor.

Repository structure

Each PCB folder contains a schematic.pdf, the KiCad project in src, and production files in production (generic, and ready to upload to JLCPCB). See pcb/README.md for the stackups and how to order the boards.

Editing the design

Requirements:

• KiCad 10 or newer
• Git LFS for STEP models, PDFs, images, and fabrication archives

git lfs install
git clone git@github.com:sedlak477/owl-hardware.git

After changing a board, regenerate its production files with pcb/export-production.sh (see pcb/README.md). Pushing a tag starting with v (e.g. v1.1.0) creates a release with the packaged production and 3D-print files.

Related resources

owl-firmware: The firmware for the OWL platform.
owl-ranger: A script for stepping through some orientations and recording measurements.
pyowl: A python library for interacting with the OWL.
Dataset: Orientation-diverse BLE Channel Sounding and UWB ranging measurements recorded with the OWL.

License

Copyright 2026 Michael Sedlak. Licensed under CERN-OHL-P-2.0, without any warranty.