STM32H7-powered open-source hardware 3D printer mainboard supports up to 6 stepper drivers

Designed by Boltz R&D, the SmartPrintCoreH7x 3D printer mainboard is an open-source mainboard built around an STM32H7 microcontroller and designed to work with 3D printers from Creality, Anet, and Voron. It supports up to 6 stepper drivers (5 standard drivers plus 1 dedicated driver) and can be expanded further using the “SmartPrintCore Extravaganza” module for additional stepper drivers.

Key features of this motherboard include a jumper-less setup, automatic power source switching, and support for both 12V and 24V power supplies. It uses high-efficiency TI buck converters to provide power for multiple fan and servo ports, and there is a dedicated power supply for peripherals, SBCs, and Wi-Fi modules. The board is equipped with a variety of connectors, including Molex, Ultra-Fit, Mini-Lock, and JST-GH for power, motors, and peripherals.

SmartPrintCoreH7x specifications:

MCU – STMicro STM32H723 Arm Cortex-M7 32-bit core @ 550 MHz with 1MB Flash, 564 KB RAM, FPU, DSP, Ethernet, USB OTG HS/FS, CAN FD
Storage – Micro SD card
Stepper ports
- Stepper Driver Ports – 5+1 (expandable in multiples of 5 via “SmartPrintCore Extravaganza”)
- Closed-Loop Stepper Ports – 5x dedicated ports
- Buffered Signals – For motor SPI and UART
Heaters
- 3x high-power heaters (15A max per port, locking connectors)
- 1x heated bed port (15A max, locking connector)
Fan
- 4x PWM-controlled ports
- 2x always-on ports
- Configurable voltages (12V, 5V, or POWER_IN)
- 2A per port, 4A total for all fans
Other ports
- 4x servo ports (2A each, 4A total across all ports)
- 4x temperature sensor ports
- 6x endstop ports
- 2x filament sensor ports
- LCD connector port
- BLTouch port
USB – USB-C with auto power switching
Serial – 2x UART ports
Expansion – 3x SPI, 2x I2C, 1x CAN Bus
Misc
- 3x Accelerometer
- Neopixel RGB LED port (1A operating, 2A max)
- Onboard slow-burning fuse with optional external inline fuses
- ESP-01 UART port
- PT100 SPI port
- Sensorless homing (DIP switch config)
- Pre-configured micro-stepping
- Buffered signals for motor SPI and UART
Power
- Input Voltage – 12V to 24V (Auto power source selection: USB/Main Supply)
- Power Input – Connector 6-in-1 Molex MegaFit (self-locking)
- Power Outputs
  - 5V @ 10A (SBC supply with locking connector and USB Type-C)
  - 5V @ 5A (Fans and peripherals)
  - 12V @ 5A (Fans and peripherals)
  - 3.3V @ 1A (Wi-Fi modules and small devices)
  - 15A bed heater supply (with locking connector)
Dimensions – 297 x 210 mm

The SmartPrintCoreH7x supports the popular open-source Marlin and Klipper firmware, making it compatible with a wide range of 3D printers. The PCB is optimized for efficient heat management and features a stable power trace layout. The board is designed to work with BeaglePlay and BeagleBone SBCs for enhanced performance and flexibility.

The company also mentions that the Marlin configuration is still under development and you need to contact them on Discord to prioritize it if necessary. Additionally, the component libraries are not included due to license restrictions, but you can join their organization as a “contributor” for access. A custom 3D-printed casing is under development and expected by May 2024. The Klipper configuration files are minimal and will require some adjustments based on your use case. For any queries or feature requests, feel free to reach out on Discord. More information, including the KiCad schematics and PCB layout, can be found on the BoltzRnD GitHub repo.

Open-source hardware 3D printer controller boards may become more popular with the recent drama around Bambu Lab who decided to lock the firmware of their 3D printers. Previously, we had also written about the Recore A8 Allwinner A64-powered 3D printer control board with TMC2209 stepper drivers, some ESP32-based 3D printer control boards such as the Phi MainBoard 5LC and PandaZhu offering low-cost options for your 3D printer.

While you could make the open-source 3D printer mainboard yourself, the SmartPrintCoreH7x can also be purchased for $134.99 on Tindie or Boltz R&D store.

Debashis Das

Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication