Gopper

A Klipper firmware implementation in TinyGo for modern microcontrollers.

Gopper brings the power of Go to 3D printer firmware, providing a modern, type-safe, and maintainable alternative to C-based implementations while maintaining full compatibility with the Klipper protocol.

Features

• ✅ Full Klipper protocol compatibility
• ✅ Written in TinyGo for optimal embedded performance
• ✅ Modular architecture for easy customization
• ✅ Type-safe implementation with Go's strong typing
• ✅ Support for modern microcontrollers
  • RP2040 (Raspberry Pi Pico) - Full support
  • RP2350 (Raspberry Pi Pico 2, Crea8) - Full support
  • STM32G0B1/H723 (planned)

Status

⚠️ Early Development - This project is in active development and not yet ready for production use.

Latest Update (2025-11-28): RP2350 now has full feature parity with RP2040! All 74 commands working including steppers, endstops (GPIO, analog, I2C), and TMC driver support.

Current Progress

Phase 1: Core Protocol (Completed ✅)

• ✅ VLQ encoding/decoding (Klipper-compatible)
• ✅ CRC16 implementation
• ✅ Buffer management (InputBuffer, OutputBuffer, FifoBuffer)
• ✅ Transport layer with message framing
• ✅ Command dispatch system
• ✅ Unit tests for all components

Phase 2: Minimum Viable Commands (Completed ✅)

• ✅ Data dictionary generation system
• ✅ Constants and enumerations registry
• ✅ Core protocol commands:
  • identify / identify_response
  • get_uptime / uptime
  • get_clock / clock
  • get_config / config
  • config_reset
  • finalize_config
  • allocate_oids
  • emergency_stop
• ✅ RP2040 hardware timer integration
• ✅ USB CDC communication (native USB support)
• ✅ Complete main loop with USB I/O

Phase 3: Peripheral Modules (In Progress ⏳)

• ✅ ADC driver infrastructure
  • ✅ RP2040: 4 channels (ADC0-ADC3) + temperature sensor
  • ✅ RP2350: 5 channels (ADC0-ADC3) + temperature sensor
  • ✅ Klipper analog_in protocol
  • ✅ Pin enumeration system
• ✅ GPIO driver infrastructure
  • ✅ RP2040: 30 GPIO pins (gpio0-gpio29)
  • ✅ RP2350: 48 GPIO pins (gpio0-gpio47)
  • ✅ Digital output/input support (pull-up/pull-down)
  • ✅ PWM capable outputs
• ✅ PWM driver infrastructure (RP2040/RP2350)
  • ✅ Hardware PWM support (8 channels)
• ✅ SPI driver infrastructure (RP2040/RP2350)
  • ✅ Hardware SPI (2 controllers with multiple pin configs)
  • ✅ Software SPI (bit-banging fallback)
• ✅ I2C driver infrastructure (RP2040/RP2350)
  • ✅ Hardware I2C communication
• ✅ Stepper driver infrastructure (RP2040/RP2350)
  • ✅ config_stepper, queue_step, set_next_step_dir, reset_step_clock
  • ✅ stepper_get_position and stepper_position response
  • ✅ stepper_stop_on_trigger for homing
  • ✅ PIO-accelerated backend (500kHz+ step rate)
• ✅ Endstop handling (RP2040/RP2350)
  • ✅ Trigger synchronization (trsync)
  • ✅ Digital, analog, and I2C endstop support
  • ✅ Coordinated multi-axis homing
• ✅ TMC driver support (RP2040/RP2350)
  • ✅ SPI and UART configuration commands
• ⏳ Heater/temperature control

Supported Hardware

Fully Supported ✅

• RP2040 (Raspberry Pi Pico)

  • 30 GPIO pins
  • Full feature support (ADC, GPIO, PWM, SPI, I2C, Steppers, Endstops)
  • PIO-accelerated stepper control (500kHz step rate)

• RP2350 (Raspberry Pi Pico 2, Crea8 board)

  • 48 GPIO pins (gpio0-gpio47)
  • Full feature support (ADC, GPIO, PWM, SPI, I2C, Steppers, Endstops, TMC drivers)
  • PIO-accelerated stepper control (up to 8 steppers via 2 PIO blocks)
  • See targets/rp2350/README.md for details

Planned

• STM32F4 series
• STM32H7 series
• More to come...

Communication

Gopper uses native USB CDC (Communications Device Class) for communication with the Klipper host. This provides:

When you flash Gopper to your board, it will enumerate as a USB serial device:

• Linux: /dev/ttyACM0
• macOS: /dev/tty.usbmodem*
• Windows: COM3 (or similar)

Recommended: Use Persistent Device Path

Instead of /dev/ttyACM0 (which can change if you have multiple USB serial devices), use the persistent /dev/serial/by-id/ path:

# List available USB serial devices by ID
ls -l /dev/serial/by-id/

# Example output:
# lrwxrwxrwx 1 root root 13 Nov 12 10:00 usb-Raspberry_Pi_Pico-if00 -> ../../ttyACM0

# Use this in your printer.cfg:
[mcu]
serial: /dev/serial/by-id/usb-Raspberry_Pi_Pico-if00

## Project Structure

gopper/ ├── protocol/ # Klipper protocol implementation ├── core/ # Core scheduling and command system ├── hardware/ # Hardware abstraction layer ├── motion/ # Motion control and kinematics ├── modules/ # Peripheral modules (steppers, sensors, etc.) ├── targets/ # Target-specific implementations └─ tinycompress/ # TinyCompress compression library (zlib compatible)

## Building

Requirements:
- TinyGo 0.31.0 or later (0.39+ recommended for RP2350)
- Go 1.21 or later (1.25 recommended)

```bash
# Build for RP2040 (Raspberry Pi Pico)
make rp2040

# Build for RP2350 (Raspberry Pi Pico 2, generic boards)
make rp2350

# Build for RP2350 (Pico 2 specifically)
make rp2350-pico2

# Build for Crea8 board (RP2350B-based, 7-axis stepper controller)
make crea8

# Build for STM32F4
make stm32f4

# Run tests
make test

# Clean build artifacts
make clean

Manual Build Commands

# Build for RP2040
tinygo build -target=pico -o build/gopper-rp2040.uf2 ./targets/rp2040

# Build for RP2350 (generic)
tinygo build -target=metro-rp2350 -o build/gopper-rp2350.uf2 ./targets/rp2350

# Build for RP2350 (Pico 2)
tinygo build -target=pico2 -o build/gopper-pico2.uf2 ./targets/rp2350

# Build for STM32F4
tinygo build -target=nucleo-f446re -o build/gopper-stm32f4.hex ./targets/stm32f4

# Run tests (protocol and core packages)
go test -v ./protocol/...
go test -v ./core/...

Testing with Klipper

Flashing Firmware

# 1. Put board in BOOTSEL/bootloader mode
#    - RP2040/RP2350: Hold BOOTSEL button while plugging in USB

# 2. Flash firmware
# For RP2040 (Pico)
cp build/gopper-rp2040.uf2 /media/$USER/RPI-RP2/

# For RP2350 (Pico 2, Crea8, etc.)
cp build/gopper-rp2350.uf2 /media/$USER/RPI-RP2/

# 3. Board should reboot and appear as USB serial device
ls -l /dev/serial/by-id/

Testing with Klipper Console

# Install Klipper (if not already installed)
git clone https://github.com/Klipper3d/klipper
cd klipper && ./scripts/install-octopi.sh

# Test with Klipper console (interactive mode)
~/klippy-env/bin/python ~/klipper/klippy/console.py /dev/ttyACM0

# Or use persistent device path
~/klippy-env/bin/python ~/klipper/klippy/console.py /dev/serial/by-id/usb-*

Example printer.cfg

For RP2040 (Full 3D printer):

[mcu]
serial: /dev/serial/by-id/usb-Raspberry_Pi_Pico-if00

[printer]
kinematics: cartesian
max_velocity: 300
max_accel: 3000

[stepper_x]
step_pin: gpio2
dir_pin: gpio3
enable_pin: !gpio4
microsteps: 16
rotation_distance: 40
endstop_pin: ^gpio16
position_endstop: 0
position_max: 200

For RP2350 (Full 3D printer - Crea8 board):

[mcu]
serial: /dev/serial/by-id/usb-Amken_LLC._Crea8_Motion_Control_Board-if00

[printer]
kinematics: cartesian
max_velocity: 300
max_accel: 3000

[stepper_x]
step_pin: gpio2
dir_pin: gpio3
enable_pin: !gpio4
microsteps: 16
rotation_distance: 40
endstop_pin: ^gpio16
position_endstop: 0
position_max: 200

# PWM output (e.g., fan)
[fan]
pin: gpio15

# ADC input (e.g., temperature sensor)
[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: ADC0
min_temp: 0
max_temp: 100

See test/klipper/ for more example configurations and targets/rp2350/README.md for RP2350-specific details.

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

Acknowledgments

• Klipper by Kevin O'Connor
• Anchor for inspiration on protocol implementation
• The TinyGo community

This project is not endorsed or affiliated with Klipper, Anchor, or TinyGo in any way. Please do not contact Klipper, Anchor, or TinyGo for support.

License

MIT License - See LICENSE for details