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link101

One Cable. (Almost) Every Protocol. Zero Driver Hell.

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LINK101 kills the USB adapter mess on robot workbenches. One Type-C cable gives you CAN-FD, RS485, Dynamixel, Feetech, UART, I2C, and MIT Cheetah-protocol ports — all as stable Linux devices. No driver hell. No reboots to fix device names. Transparency mode is for getting your robot running fast. LINK101 acts as a protocol bridge. Your existing ros2_control setup, vendor drivers, and launch files work without modification. The board exposes every bus as a standard Linux interface — /dev/axon-can, /dev/axon-rs485, and so on. You don't write any firmware. You just plug it in and your hardware shows up where your existing code expects it. Standalone mode is for when you need determinism. The RP2350 runs a ROS 2 node on the MCU using zenoh-pico over USB CDC. Time-critical control loops move off the host OS entirely. No scheduling jitter. No missed deadlines. This requires writing application-specific firmware, but the SDK and a project template are provided.

Features and Specifications

MCU: Raspberry Pi RP2350 (dual Cortex-M33 at 150 MHz, 520 KB SRAM, 2 MB flash)

Motor and Sensor Buses

  • CAN bus: MCP2518FD transceiver, CAN-FD capable
    • XT30(2+2) connector for MIT Cheetah protocol (Damiao, CubeMars, Unitree, MyActuator)
    • JST-GH 4-pin connector for ODrive protocol
    • Screw Terminals for everything else
  • RS485: hardware UART with transceiver (XH2.54 connector)
    • Feetech and Dynamixel connectors
    • Screw Terminals and 2.54mm Pin Headers for everything else
  • Half-duplex UART: 1x bus compatible with Feetech SCS/STS, Dynamixel Protocol 1.0 and 2.0, FashionStar bus servos (Dynamixel and Molex connectors)
  • Full-duplex UART: 2x serial ports, one with 5V level shifter (XH2.54 connectors)
    • Waveshare DDSM, GPS modules, BMS, lidars, generic serial devices
  • I2C: hardware I2C with Qwiic/STEMMA QT (JST-GH 4-pin connector)
    • SparkFun, Adafruit STEMMA QT, Seeed Grove compatible sensors, displays, and expanders

Onboard Sensors and I/O

  • USB Type-C composite device with multiple interfaces (CDC serial ports, SocketCAN, debug)
  • Stable udev device names (e.g. /dev/axon-rs485, /dev/axon-can)
  • IMU: LSM6DSOTR 6-axis (accelerometer + gyroscope), and
  • NeoPixel LED per protocol bus for visual status and debugging
  • 7x GPIO and 4x ADC ports for further extension

Open Source

link101 is open source across the stack. Hardware design files (KiCad schematics, PCB layout, fabrication outputs, BOM) and module footprints are released under CERN-OHL-W v2. Firmware SDK, protocol drivers, and ROS 2 packages are released under the MIT license. Custom carrier boards that use the module do not need to be open-sourced.

For standalone mode, the firmware SDK exposes a clean interface for adding protocol support: implement a small set of functions, register a protocol name, and you have a working driver.

We strongly encourage sharing drivers back to the community via pull request. Once merged, every user gets access to the new protocol, and the contributor is credited in the project. In bridge mode, no firmware development is needed at all since existing host-side ROS2 packages and vendor tools work directly over the exposed Linux devices.

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