Laser CANbus Toolhead

🔥 Laser CANbus Toolhead PCB

🌍 Languages: English | Deutsch

A compact, robust toolhead board for Klipper-based laser engravers and cutters (CoreXY). This board integrates power supply, laser driver logic, CAN-Bus communication, and input shaping (ICM-20602) in the smallest possible space.

📚 Contents

• 🔥 Laser CANbus Toolhead PCB
  • 📚 Contents
  • ✨ Features
    • 🧠 Microcontroller
    • 🔗 CAN-Bus Communication
    • 📊 Input Shaping
    • ⚡ Laser Power Control
    • 🎛️ Laser Signal Control
    • 🔌 Power Supply
    • 🚨 Diagnostics & Monitoring
  • 📋 Klipper Configuration
    • Basic MCU Setup
    • Input Shaping (ICM-20602)
    • Laser Control
  • 🔌 Pinout & Connector Assignment
    • J101 - Power & CAN Input (Micro-Fit 3.0, 2x2, THT)
    • J102 - Laser Output (Micro-Fit 3.0, 1x3, THT)
    • Debug/Programming Header (Back Side)
  • 🔧 Installation & Setup
    • 1. CAN-Bus Configuration
    • 2. Firmware Flash
    • 3. Find UUID
  • ⚠️ Safety Notes
  • 🛠️ BOM (Bill of Materials) - Highlights
  • 🛠️ Technical Specifications
  • 📝 Changelog
    • Rev. 1
    • Rev. 0 (Initial Release)
  • 📚 Additional Resources
  • License

✨ Features

🧠 Microcontroller

• MCU: STM32F072CBU6 (Cortex-M0, 48MHz, CAN-capable)
• Stability: 12MHz crystal for maximum CAN-Bus stability
• Firmware: Klipper-compatible

🔗 CAN-Bus Communication

• Transceiver: SN65HVD230 with ESD protection
• Termination: Split termination via solder jumper
• Slope Control: Switchable for EMI optimization

📊 Input Shaping

• Sensor: On-board ICM-20602 accelerometer/gyroscope (SPI)
• Purpose: Klipper resonance measurement for perfect print quality
• Advantage: Better availability and modern sensor technology

⚡ Laser Power Control

• Circuit: 24V / 6A High-Side Switch (CJAC70P06 P-MOSFET, 60V rated)
• Peak Current: 8A capability
• Soft-Start: Limits inrush current (Rise-time ~1.2ms)
• Safety: Hardware pull-down prevents unwanted activation
• Limitation: Max 6A limited by Micro Fit 3.0 connector with 0.75mm² wire

🎛️ Laser Signal Control

• PWM: 5V Level-shifted via 74AHCT1G125 buffer
• Quality: Clean edges, true hardware PWM via STM32 timer
• Compatibility: Common diode lasers

🔌 Power Supply

• Input: 24V with 250mA PTC fuse and SMF24A TVS diode
• 5V Rail: MP2459 Buck converter (up to 60V input tolerant)
• 3.3V Rail: XC6206 LDO for MCU and peripherals

🚨 Diagnostics & Monitoring

• Power LEDs: 24V In, 24V Sys, 5V, 3.3V
• Status LEDs: Laser Enable, Laser PWM, Heartbeat

📋 Klipper Configuration

Basic MCU Setup

[mcu toolhead]
canbus_uuid: <your-uuid>  # Find with "ls /dev/serial/by-id/*" or "~/klippy-env/bin/python ~/klipper/scripts/canbus_query.py can0"

[temperature_sensor toolhead_mcu]
sensor_type: temperature_mcu
sensor_mcu: toolhead

Input Shaping (ICM-20602)

[mpu9250]
cs_pin: toolhead:PA4
spi_bus: spi1
#axes_map: x,y,z  # Configure according to your printer orientation

[resonance_tester]
accel_chip: mpu9250
probe_points:
    150, 150, 20  # Adjust to your bed size

Laser Control

# Laser PWM Signal
[output_pin laser_pwm]
pin: toolhead:PB14
pwm: True
cycle_time: 0.001          # 1kHz PWM frequency
shutdown_value: 0          # Safety: laser off during emergency

# Laser Enable (optional)
[output_pin laser_enable]
pin: toolhead:PB15
value: 0
shutdown_value: 0

# Heartbeat LED (optional)
[output_pin heartbeat]
pin: toolhead:PA9
pwm: True
cycle_time: 1.0

🔌 Pinout & Connector Assignment

J101 - Power & CAN Input (Micro-Fit 3.0, 2x2, THT)

J102 - Laser Output (Micro-Fit 3.0, 1x3, THT)

Debug/Programming Header (Back Side)

💡 Bootloader Mode: To force the STM32 into DFU/Bootloader mode (e.g., for initial flash with Katapult), bridge the BOOT0 pad with 3.3V during power-on.

🔧 Installation & Setup

1. CAN-Bus Configuration

• Set CAN-Bus termination according to position in network
• Baud rate: 1 Mbit/s (Klipper standard)

2. Firmware Flash

1. Put board into DFU mode (bridge BOOT0)
2. Compile Klipper for STM32F072 with CAN support
3. Flash firmware: make flash FLASH_DEVICE=<dfu-device>

3. Find UUID

~/klippy-env/bin/python ~/klipper/scripts/canbus_query.py can0

⚠️ Safety Notes

• Laser Safety: Always wear protective eyewear
• Power Supply: Only operate with 24V DC
• Initial Setup: Slowly ramp up laser power
• Emergency: Hardware pull-down ensures safe state

🛠️ BOM (Bill of Materials) - Highlights

🛠️ Technical Specifications

📝 Changelog

Rev. 0.1

• Transistor Upgrade: Replaced MOSFET with CJAC70P06 (60V voltage rating)
• Sensor Upgrade: Changed from ADXL345 to ICM-20602 (better availability, modern 6-axis IMU)
• Connector Change: Micro Fit 3.0 connectors changed from SMD to THT mounting
• Silkscreen Enhancement: Added connector pin assignments to silkscreen for easier assembly
• Layout Improvements: Cleaned up component placement and optimized routing
• Documentation: Updated overview image to reflect current design
• BOM Update: Added component order numbers and updated production data
• Production Files: Updated assembly and production files with current components

Rev. 0.0 (Initial Release)

• Initial PCB design with STM32F072CBU6 microcontroller
• CAN-Bus communication with SN65HVD230 transceiver
• 24V/4A laser power control with AO4407A MOSFET
• ADXL345 accelerometer for input shaping
• MP2459 buck converter for power supply

📚 Additional Resources

• Klipper Documentation
• CAN-Bus Setup Guide
• Input Shaping
• Katapult Firmware Flasher

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.