Adding CANBus to an Existing Voron Build

CANBus Electronics Retrofit Toolhead

If you built your Voron with traditional wiring — a thick umbilical cable running from the mainboard to the toolhead — you’ve probably experienced the downsides: cable drag affecting print quality, difficulty swapping hotends, and the headache of diagnosing a broken wire buried inside the cable chain. Retrofitting CANBus to an existing Voron is one of the highest-impact upgrades you can make. It simplifies your toolhead wiring from 10+ wires down to just 4, dramatically reduces cable drag, and makes future maintenance far easier. Last updated: May 2025.

This guide covers retrofitting CANBus to any existing Voron printer: V2.4, Trident, V0.2, Switchwire, or custom builds. We’ll go through the required components (U2C adapter, EBB toolhead board, CAN cable), how to retrofit without fully disassembling your printer, wiring strategies for different Voron models, and the complete Klipper configuration process.

What Is a CANBus Retrofit?

A CANBus retrofit replaces the traditional multi-wire toolhead umbilical with a CAN bus network. Instead of running 10-14 individual wires from your main controller board to the toolhead, you install a secondary MCU (the EBB toolhead board) directly on the toolhead, and run just 4 wires: 24V power, ground, CAN_H, and CAN_L. The EBB board handles all local I/O — hotend heater, thermistor, fans, extruder stepper, probe — and communicates with your SBC over the CAN bus using just two data wires.

The key insight for a retrofit: you don’t need to replace your mainboard. The CAN bus connects to your existing SBC (Raspberry Pi, CB1, or similar) via a USB-to-CAN (U2C) adapter. Your existing mainboard continues to handle X/Y/Z motion and the heated bed. The toolhead MCU (EBB board) handles everything on the moving carriage.

Benefits of Retrofitting CANBus

Dramatically reduced cable drag: This is the #1 reason Voron builders switch to CANBus. A traditional 14-wire umbilical creates significant drag on the toolhead as it flexes through the cable chain. On a V2.4 with high acceleration (5,000-10,000 mm/s^2), this drag manifests as ringing, ghosting, and artifacts in prints — especially in Y-axis movements. The 4-wire CAN cable is much lighter and more flexible, reducing drag by an estimated 60-70%.

Toolhead swaps in 30 seconds: Once on CANBus, swapping a hotend or the entire toolhead means unplugging one 4-pin connector. No more disconnecting individual wires from the mainboard, no more rerouting cables, no more checking which wire goes where. This is a game-changer if you like experimenting with different hotends (Dragon vs Rapido vs Revo).

Better print quality at high speeds: The reduced cable drag means your input shaper calibration will show lower vibration amplitudes. Users consistently report being able to run 10-20% higher acceleration values after CANBus conversion while maintaining the same print quality.

Cleaner wiring overall: The 4-wire CAN cable is easier to route, produces less clutter, and looks significantly cleaner. If you care about the aesthetics of your build, this alone is worth the upgrade.

Parts Needed — China-Direct Pricing

Note: If you already have a crimping tool and JST connectors from your build, you can skip the connector kit. Pre-made CAN cables are worth the small extra cost — they come with proper twisted pairs and shielding, which is critical for reliable CAN communication at 1 Mbps.

Difficulty Level and Time Required

Difficulty: Intermediate to Advanced. You need to be comfortable with Klipper firmware compilation and flashing via DFU. The physical installation is straightforward (mount board, run cable, connect wires), but the firmware side (configuring Klipper for CAN, UUID discovery, pin mapping) requires attention to detail.

Time required: 3-5 hours for a first-time retrofit on a V2.4 or Trident. V0.2 takes about 2-3 hours (less cable to route). This includes firmware compilation, physical installation, wiring, configuration, and testing.

Step-by-Step Retrofit Process

Step 1: Choose Your Toolhead Board

The two main options are the BTT EBB36 and the Mellow FLY-SHT36. Both work identically once configured. The EBB36 is more widely documented; the FLY-SHT36 has removable terminal blocks that some find easier to work with. For a StealthBurner toolhead, the EBB36 fits perfectly in the cable channel at the back. For a Mini AfterBurner, you may need a printed adapter mount (freely available on Printables/Thingiverse).

Step 2: Compile and Flash Klipper on the U2C

The U2C adapter needs Klipper firmware configured as a USB-to-CAN bridge:

1. cd ~/klipper && make menuconfig
2. Microcontroller: STM32G0B1 (BTT U2C V2.1) or STM32F072 (Mellow U2C)
3. Communication interface: USB to CAN bus bridge
4. CAN bus interface: CAN bus (on PB0/PB1)
5. CAN bus speed: 1000000 (1 Mbps)
6. make then flash via DFU: hold BOOT button, plug into SBC USB, dfu-util -a 0 -D out/klipper.bin --dfuse-address 0x08000000:leave

Step 3: Compile and Flash Klipper on the EBB Board

1. cd ~/klipper && make menuconfig
2. Microcontroller: STM32G0B1 (EBB36/42 V1.2)
3. Communication interface: CAN bus (on PB0/PB1)
4. CAN bus speed: 1000000 (must match U2C)
5. make then flash via DFU

Step 4: Physical Installation — Mount the U2C

Mount the U2C adapter inside your electronics bay. It has mounting holes for M3 screws. Place it near your SBC so the USB cable reaches easily. Connect the SBC to the U2C via USB-C. Power the U2C by connecting 24V and GND from your PSU or mainboard power input — the U2C needs 24V to power the CAN transceiver.

Step 5: Physical Installation — Mount the EBB Board on the Toolhead

For a StealthBurner toolhead: there’s a dedicated recess on the back of the right body half for the EBB36. The board slides in and is retained by the toolhead screws. Connect your toolhead components to the EBB board:

• Hotend heater: Connect to the HE0/HE1 terminals (24V output, up to 3A). Use 18-20 AWG silicone wire.
• Thermistor: Connect to the TH0/TH1 terminals (use twisted pair wire). Polarity doesn’t matter for standard NTC thermistors.
• Extruder stepper: Connect to the motor terminals (A1/A2/B1/B2). Use 24 AWG wire.
• Part cooling fan: Connect to FAN0 or FAN1 header. The EBB provides 24V PWM output.
• Hotend fan: Connect to another fan header, or wire it to the 24V input directly if it should run whenever the printer is on.
• Probe: Connect the probe signal, ground, and 5V/VCC to the appropriate pins. The EBB has dedicated probe and endstop headers.

Step 6: Run the CAN Cable

Route the 4-wire CAN cable from the electronics bay to the toolhead, through the cable chain. If your existing cable chain is too narrow for the 4-wire cable plus the X/Y motor wires, you may need a wider cable chain (common on older V2.4 builds with 6mm chain). The CAN cable connects:

• Red: 24V (from PSU/U2C input to EBB 24V input)
• Black: GND (from PSU ground to EBB ground)
• White/Yellow: CAN_H (from U2C CAN_H terminal to EBB CAN_H pin)
• Green/Blue: CAN_L (from U2C CAN_L terminal to EBB CAN_L pin)

Enable the 120 ohm termination resistor jumper on both the U2C adapter and the EBB board. These are the two ends of the CAN bus. If you add more CAN devices later, do not enable termination on those.

Step 7: Bring Up the CAN Interface and Discover UUID

1. On the SBC: sudo ip link set can0 up type can bitrate 1000000
2. Run: ~/klipper/scripts/flash_can.py -q
3. Note the UUID returned (e.g., abcdef123456)

If no UUID appears, check power to both U2C and EBB, check termination resistors, and verify CAN_H/CAN_L are not swapped.

Step 8: Configure printer.cfg for CAN

Add the CAN MCU section:

[mcu toolhead]
serial: canbus_uuid:abcdef123456
canbus_interface: can0


Then move all toolhead-related sections (extruder, heater_fan, fan, probe, etc.) to use the toolhead MCU. If your original config had [extruder] on the mainboard MCU, add stepper: to point to the toolhead MCU’s stepper driver, or use the EBB’s integrated TMC2209.

[extruder]
step_pin: toolhead:PB0
dir_pin: toolhead:PC5
enable_pin: !toolhead:PC4
microsteps: 16
rotation_distance: 22.68 # LGX Lite/Orbiter: check your extruder
nozzle_diameter: 0.400
filament_diameter: 1.750
heater_pin: toolhead:PA1
sensor_type: Generic 3950
sensor_pin: toolhead:PC1
control: pid
pid_Kp: 22.2
pid_Ki: 1.08
pid_Kd: 114
min_temp: 0
max_temp: 270


Compatibility Notes

V2.4 compatibility: The V2.4 benefits most from CANBus due to the long cable chain (Z-axis movement) and high-speed operation. The EBB36 fits perfectly in the StealthBurner’s rear channel. Note that the V2.4’s standard 6mm cable chain may need replacement with 8mm or 10mm chain if your existing bundle includes 4 motor wires + CAN cable. The 10mm chain is recommended for new builds and retrofits.

Trident compatibility: Identical to V2.4 in terms of toolhead mounting. The Trident’s fixed bed means the cable chain is shorter and simpler to route. The shorter chain also means you can use a 1m CAN cable instead of 1.5m.

V0.2 compatibility: The V0.2 has a very small electronics bay. The U2C adapter may not fit inside — you can mount it externally or use a USB-to-CAN hat that plugs directly onto the Pi’s GPIO. The EBB36 fits in the mini-StealthBurner with a printed adapter. The V0.2’s tiny cable chain may need replacement.

Switchwire compatibility: The Switchwire’s toolhead carriage has limited space. The EBB42 is usually a better fit than the EBB36 for the Switchwire due to the different mounting pattern. You may need a printed adapter plate.

Before and After Comparison

Common Pitfalls

• CAN_H and CAN_L swapped: The most common mistake. If discovery fails, swap these two wires. The U2C and EBB both use screw terminals or JST connectors — it’s easy to mix them up.
• Missing termination resistor: Both ends of the CAN bus need 120 ohm termination. Without it, the signal reflects and communication fails or becomes unreliable. If you get intermittent UUID detection, check the jumpers first.
• Voltage drop on 24V: The CAN cable’s 24V wires must be thick enough. Thin wires (24 AWG or thinner) cause voltage drop that browns out the EBB board during high-current operations (heater + stepper running simultaneously). Use at least 20 AWG for the power pair.
• CAN interface not coming up: The command sudo ip link set can0 up type can bitrate 1000000 must run at boot. Add it to /etc/rc.local or use a systemd service. If you forget, the CAN interface won’t exist and Klipper won’t connect.
• Bitrate mismatch: The U2C and EBB must use the same CAN bitrate. Mixing 500 Kbps and 1 Mbps is a common issue if you flash one board from an older guide. Stick to 1 Mbps (1000000) for both.
• No hotend heater output: After moving the heater to the EBB, check that the heater_pin is correct. The EBB’s heater MOSFET is typically on PA1 or PA2. If the heater pin is wrong, Klipper won’t report an error — the heater just won’t turn on.
• Stepper direction reversed: The EBB’s TMC2209 may have a different pin mapping than your extruder’s previous driver. If the extruder runs backward, swap the dir_pin polarity (!dir_pin) or swap two motor wires (A with B, not A1 with A2).