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🔌 Universal Voron Power & CAN HAT (EWS)

🌍 Languages: English | Deutsch

A universal interface board (HAT) for Raspberry Pi 4/5 and Radxa Rock 5B designed for use in Voron 3D printers. Provides powerful 5V supply (8A), CAN-Bus interface (USB-Bridge or Native), USB hub, and fan control.

📚 Contents

🔌 Universal Voron Power & CAN HAT (EWS)

🎯 About EWS

EWS stands for "Eierlegende Wollmilchsau" (German for "egg-laying woolly milk pig") - a humorous term for a universal solution that does everything. This HAT lives up to its nickname by combining multiple essential functions for Voron 3D printer control systems in a single, compact board.

The board addresses common pain points in Voron builds by providing robust power distribution, reliable CAN communication, and convenient USB connectivity while maintaining compatibility with both Raspberry Pi and Radxa Rock 5B single-board computers.

✨ Features

🔋 Power Supply (24V Input)

Input Voltage: 24V DC nominal
Connectors: XT30PW-F (horizontal) or 5.08mm screw terminal
Reverse Polarity Protection: P-Channel MOSFET (CJAC70P06, -60V, -70A, RDSon ~8mOhm)
MOSFET Gate Protection: 15V Zener diode (BZT52C15S) between Source and Gate
Voltage Divider: 30kOhm (Gate-Source) and 30kOhm (Gate-GND)
Overvoltage Protection: TVS diode (SMAJ26A, 26V Standoff, Unidirectional) placed AFTER MOSFET to GND
Input Protection: Distributed fusing (5A for DC/DC, 5A each for CAN ports)

⚡ DC/DC Converter (5V Output)

Controller: MaxLinear XR76208 (Synchronous Step-Down, 8A, COT)
Input Fuse: 5A SMD 1812 Slow Blow
Output Voltage: 5.25V (set via feedback divider: R_Top=15.5kOhm, R_Bottom=2.0kOhm)
Switching Frequency: ~600kHz (set via Ron=30kOhm)
Inductance: 3.3µH Shielded (Sunlord MDA1050-3R3M, Isat ~17A)
Input Capacitors: 4x 10µF 1206 ceramic + 1x 100µF electrolytic/polymer (bulk)
Output Capacitors: 4x 22µF 1206 ceramic
Stability: Feed-forward capacitor (Cff) 1nF parallel to upper feedback resistor
Soft-Start: 100nF at SS pin (~6ms startup time)
Current Limit: 5.6kOhm resistor at ILIM pin
Enable: Voltage divider from 24V (100kOhm upper, 22kOhm lower) = ~4.3V at pin

🔌 Logic Power Supply (Power Path)

Concept: Separation of +5V_PWR (high current for screen/webcam) and +5V_LOGIC (for MCU/Hub)
Diode OR-ing: 2x Schottky diodes (1N5819WS, 1A)
- Source 1: USB_VBUS (from Pi/PC) → Diode → +5V_LOGIC
- Source 2: +5V_BUCK (from 8A regulator) → Diode → +5V_LOGIC
Purpose: Board is USB-flashable without 24V supply, no backflow to PC
3.3V Generation: LDO (XC6206) powered from +5V_LOGIC

🧠 MCU & CAN Interface

Microcontroller: STM32G0B1KBU6 (UFQFPN-32)
Clocking: Crystal-less (Internal HSI48 with Clock Recovery System CRS via USB)
Pi Connection:
- USB (PA11/PA12) to USB Hub
- UART (PA9/PA10) to Pi Header (Pin 8/10) via jumperable connection
- NRST to Pi GPIO 22 (via 1kOhm) + button to GND + 100nF cap
- BOOT0 (Pin 24/PA14 shared with SWCLK) to Pi GPIO 27 (via 1kOhm) + button to 3.3V + 10kOhm pull-down
CAN Transceiver: MCP2542WFD (or compatible)
Muxing: Jumper selectable between STM32 (USB-CAN Bridge) and Rock/Pi Native GPIOs (Pin 3/5)
Termination: 120 Ohm resistor, switchable per DIP switch (directly at connectors)
CAN Connectors: 2x Molex Micro-Fit 3.0 (2x2)
Micro-Fit Pinout: Pin 1=24V, Pin 2=GND (upper row), Pin 3=CAN_H, Pin 4=CAN_L (lower row)
CAN Power Protection: 5A SMD 1812 Slow Blow per port

📡 USB Hub

Controller: WCH CH334F (QFN-24)
Speed: USB 2.0 High Speed (480 Mbit/s) with MTT
Clocking: Internal (crystal-less), XI/XO pins left open
Supply: V5 to +5V_LOGIC
Upstream: To Raspberry Pi Header (USB loopback cable required) or USB-C input
Downstream Ports:
- STM32 (internal)
- USB-C connector (for touchscreen)
- USB-A connector (vertical, for webcam)
- JST-XH header (internal, pinout: 5V, D-, D+, GND)

USB Port Protection:

Concept: 100µF electrolytic tank at +5V_PWR, followed by polyfuse, followed by 22µF ceramic at connector
USB-C Port (Screen):
- Polyfuse: 4.0A hold current (hot chamber derating considered)
- CC Lines: CC1 and CC2 each with 10kOhm resistor to VBUS (behind fuse) for 3A advertisement
- ESD Protection: SRV05-4 TVS array
USB-A Port (Webcam):
- Polyfuse: 1.5A hold current
- ESD Protection: SRV05-4 TVS array

🌊 Fan Control

Connector: Dual-footprint JST-XH (2.54mm) and JST-PH 2-pin parallel
Driver: N-Channel MOSFET (AO3400)
STM32 Pin: PA8 (Timer 1, hardware PWM capable)
Fail-Safe: 10kOhm pull-up resistor from gate to 3.3V (fan runs 100% during reset/flash)
Gate Series Resistance: 1kOhm

📋 Klipper Configuration

Basic MCU Setup

[mcu hat]
canbus_uuid: your_uuid_here
# Alternative for USB connection:
# serial: /dev/serial/by-id/usb-katapult_stm32g0b1xx_your_id-if00

[temperature_sensor hat_mcu]
sensor_type: temperature_mcu
sensor_mcu: hat

Fan Control

[temperature_fan mcu_fan]
pin: hat:!PA8
# Note: Inverted due to fail-safe pull-up logic
sensor_type: temperature_mcu
sensor_mcu: hat
max_power: 1.0
shutdown_speed: 1.0
cycle_time: 0.01
hardware_pwm: True
target_temp: 50.0
min_temp: 10
max_temp: 80
control: pid
pid_kp: 1.0
pid_ki: 0.5
pid_kd: 2.0

🔌 Pinout & Connector Assignment

Power Input

XT30PW-F (horizontal) or 5.08mm Screw Terminal
- Pin 1: +24V
- Pin 2: GND

CAN-Bus Ports

2x Molex Micro-Fit 3.0 (2x2, THT)
- Pin 1: +24V (upper row, left)
- Pin 2: GND (upper row, right)
- Pin 3: CAN_H (lower row, left)
- Pin 4: CAN_L (lower row, right)

USB Ports

USB-C: Touchscreen connection (5V/3A capability)
USB-A: Webcam connection (vertical mount)
JST-XH Internal: 5V, D-, D+, GND

Fan Control

JST-XH/PH 2-pin: PWM fan control (5V switching)

🛠️ PCB Specifications

Parameter	Specification
Form Factor	Standard HAT (65mm x 56mm)
Layer Stack	4-Layer Multilayer
Layer 1 (Top)	Signal/Power
Layer 2	GND Plane
Layer 3	5V Power Plane
Layer 4 (Bottom)	Signal/GND
Solder Mask	Black Matte
Surface Finish	ENIG (Gold)
Silkscreen	White
Mounting	Inner mounting holes (Pi/Rock compatible)
EMI Design	Mounting holes via-stitched to GND planes (Layer 2 & Bottom), isolated from 5V plane (Layer 3)

⚠️ Manufacturing Recommendations

PCB Manufacturing

Copper Weight: 2oz copper recommended for improved thermal performance and current handling
Via Specifications: Minimum 12-20 vias at DC/DC output for thermal management
Impedance Control: 90 Ohm differential for USB traces (D+/D- pairs)

Assembly Notes

24V Path: Minimum 3mm trace width on top & bottom layers for 12A total current
5V Distribution: Use Layer 3 plane with solid connections (no thermals) to headers and capacitors
Thermal Management: QFN GND pads connected with vias, considering bottom layer routing

Component Sourcing

Ensure polyfuse derating for chamber temperatures up to 60°C
Select inductors with sufficient saturation current (>15A recommended)
Use low-ESR capacitors for switching regulator

🛠️ Technical Specifications

Parameter	Value	Unit
Input Voltage	24 ± 2	V
5V Output Current	8	A
Logic Supply Current	2	A
CAN Baud Rate	up to 1	Mbit/s
USB Speed	480	Mbit/s
Fan Control	PWM, 5V switching	-
Operating Temperature	-10 to +70	°C
Dimensions	65 x 56	mm

📚 Additional Resources

License

This project is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0).

This means you are free to:

Share — copy and redistribute the material in any medium or format
Adapt — remix, transform, and build upon the material

Under the following terms:

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made
NonCommercial — You may not use the material for commercial purposes
ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license

For the full license text, visit: https://creativecommons.org/licenses/by-nc-sa/4.0/

Note: The original documentation is in German (README.de.md). This English version is a translation for international users.

11 KiB Raw Blame History

🔌 Universal Voron Power & CAN HAT (EWS)

📚 Contents

🎯 About EWS

✨ Features

🔋 Power Supply (24V Input)

⚡ DC/DC Converter (5V Output)

🔌 Logic Power Supply (Power Path)

🧠 MCU & CAN Interface

📡 USB Hub

🌊 Fan Control

📋 Klipper Configuration

Basic MCU Setup

Fan Control

🔌 Pinout & Connector Assignment

Power Input

CAN-Bus Ports

USB Ports

Fan Control

🛠️ PCB Specifications

⚠️ Manufacturing Recommendations

PCB Manufacturing

Assembly Notes

Component Sourcing

🛠️ Technical Specifications

📚 Additional Resources

License

11 KiB

Raw Blame History