X1Plus Expander is the hardware companion to the X1Plus open-source custom firmware distribution for Bambu Lab’s X1 3D printers. It extends your printer’s functionality with an Ethernet port, two USB ports, a STEMMA-compatible I²C connector, and four interchangeable GPIO headers for expansion modules.

X1Plus Expander is a compact, easy-to-use solution whether you’re a print farmer in search of reliable connectivity and a status indicator, a Home Assistant power user looking to integrate environmental sensors, a content creator who needs to automate high-quality photography, or just someone who wants a little more LED bling on and around their printer (for reasons either practical or aesthetic).

A Perfect Fit

X1Plus Expander plugs into your X1 between the AP board and the chamber-monitoring camera. It hosts a Microchip LAN9514 that operates as a USB hub, a 100-megabit Ethernet controller, and a Raspberry Pi RP2040 to handle GPIO controls. It also includes voltage regulators to step down from the printer’s main 24 V power supply, providing reliable 5 V and 3.3 V power without loading the AP’s regulators.

X1Plus Expander tucks away behind the X1’s LCD screen in an enclosure that you can print yourself. If you would rather get started right out of the box, you can order a high-quality print of the enclosure from us. X1Plus Expander has four expansion headers on the top for add-on modules.

Exciting Expansion Opportunities

We’ve made several add-on modules available for X1Plus Expander:

• The Addressable-LED Level Shifter Module allows you to connect a string of WS2812B-compatible LEDs (commonly known as "NeoPixels"). Short LED strips (not more than 500 mA) can be powered directly from X1Plus Expander. For longer strips, you can inject power using an external 5 V power adapter.
• The Andon Module includes 25 programmable RGB LEDs, a few buttons, and a beeper. It provides visual and auditory feedback regarding a printer's status, which is extremely useful if you're operating a print farm. Learn at a glance whether a print has completed, failed, or entered some other programmable state.
• The Shutter Release Module has two 2.5 mm, TRS-style shutter-release connectors, allowing you to wire your printer up to a camera and take reliable time-lapse photographs of your prints from all different angles. This interface is the de facto standard for shutter-release accessories, and inexpensive 2.5 mm adapter cables are readily available to match many brands of camera.

Take Action With Actions

To support the new capabilities of X1Plus Expander, we’ve designed a first-class Actions subsystem into the X1Plus firmware. X1Plus Actions connect many different triggers in the printer to perform chains of commands. For instance, you could…

• Use a G-code trigger in the middle of a print to beep when you've reached a certain layer.
• Trigger on a button press to jog the Z-axis of the bed up and down.
• Pause without shutting down the motion system at a certain layer of the print, then command a GPIO to trigger an external device. The action can then wait for another GPIO to indicate that the external device is ready before continuing.
• Build a cold-pull macro that heats the nozzle, sounds the buzzer to indicate that the nozzle has reached the right temperature, waits for you to press a button to confirm that you're pulling on the filament, then extrudes backwards.
• Use a G-code trigger to fire an external camera shutter release on every layer after moving the nozzle to a certain position to get a beautiful, smooth time lapse.

The possibilities are endless! And if you need a feature that’s not currently available in the X1Plus system, actions and triggers are defined in the open-source X1Plus Daemon, which is written in Python, so you can add your own actions or interface with whatever hardware module you might dream up.

For Everything Else, There’s GPIO

We are initially offering three modules for X1Plus Expander, and of course you’ll have that I²C interface as well. Beyond that, each module interface is wide-open with eight GPIOs. If you want to attach other peripherals to your printer, you can hook them up with 0.1 inch jumper cables or you can fab out a board with a keyed 16-pin connector if you need a reliable interface. X1Plus Expander also looks for an I²C EEPROM on pins 6 and 7 of each interface to automagically detect what module is attached to each port on boot. Each GPIO port has:

• Power:
  • Four ground pins
  • Two 3.3 V pins (maximum 1 A total across all ports)
  • Two 5 V pins (maximum 2 A total across all ports and USB)
• I/O:
  • One pin connected to an ADC/SIO/PIO pin on the RP2040
  • Six pins connected to SIO/PIO RP2040 pins
  • One pin connected to an SIO-only RP2040 pin

X1Plus Expander ships with an RP2040 firmware that supports I²C and WS2812B-compatible LED strips on specific pins and GPIO on all pins. But, like everything else in the X1Plus ecosystem, that firmware is open source, so you can modify it to suit your needs. (Or, better yet, so you can submit a patch and improve X1Plus for the rest of us!)

Features & Specifications

• Integrated 24 V to 5 V Buck regulator, separate from the AP board, capable of supplying up to 2.5 A
• Microchip LAN9514 combination USB hub and Ethernet controller, powering:
  • One 10/100 Mbps Ethernet port
  • Two USB 2.0 Type-A ports
• Raspberry Pi RP2040 GPIO controller, powering:
  • Four rectangular, 0.1 inch GPIO connectors, with 5 and 3.3 V power available
  • Automatic detection of inserted modules
  • One 3.3 V, STEMMA-compatible (JST PH) I²C connector (shared with the left-most GPIO connector's RP2040 interface)
• Wiring harness that connects to the printer's AP board and power supply
• Three optional modules:
  • An addressable-LED level shifter module
  • A shutter release module capable of driving most digital cameras
  • A configurable andon module that provides visibility into printer status

Comparisons

¹ Works in conjunction with the X1Plus custom firmware, which requires rooting your printer

Support & Documentation

The X1Plus firmware modifications for the X1 are open source software that you can easily install on your X1. X1Plus Expander and its modules are open hardware, developed on GitHub and designed with KiCad.

The CAD files for X1Plus Expander’s mount were designed in OnShape. Exports of the STEP files used to build it are available in the X1Plus Expander GitHub repository.

The project updates give a high-level overview of the development of X1Plus Expander. But if you’d like to see the nitty-gritty details of how it’s all coming together, be sure to check out our Hackaday project page! You can read about X1Plus itself on the X1Plus Wiki, and you can join a vibrant community chatting about X1Plus (and all sorts of other Bambu-related topics) on Discord.

Acknowledgments

This project would not have been possible without help from a great many people. Thanks in particular to Nixiebunny, who drove much of the hardware effort for X1Plus Expander’s add-in modules, pushed for prototype manufacturing, co-designed the main Expander board, and generally made sure that this project came together. Thanks (in no particular order) to Jon, Doridian, Balázs Triszka, crc32, Riptide, Wolf on Air, and Wolf with Sword, for their invaluable contributions to the X1Plus software; to the poor Crowd Supply project managers who had to edit my engineer writing; and to the myriad other creators who have contributed their time to answer my trivial questions. I would also like to express my gratitude to everyone in wider the X1Plus community, which made this project worth the effort! The lovely music in the campaign video is "Yellow", by Scott Buckley, released under the Creative Commons CC-BY 4.0 license. Finally, as you’ve probably figured out, X1Plus is not affiliated with or endorsed by Bambu Lab. They have not tested X1Plus Expander for compatibility with any particular printer, nor have they approved or authorized these modifications in any way.