SKR PRO V1.2 – Motherboard for 3D Printers - EXSKR1.2

• Microcontroller parameters:
  • Programmable flash memory: 1024 kB
  • SRAM memory : 192kb
  • General-purpose input/output pins: 114
  • Analog inputs: 2-bit ADC
  • UART ports: 4 hardware serial ports
  • I2C, SPI, CAN,
  • LAN: built-in network support
  • USB 2.0 communication: built into the microcontroller STM32F407ZGT6
  • Maximum allowable current per input/output pin: 20mA
  • Support for SD card
• Buttons: RESET button for easy restart
• Supported stepper motor drivers: TMC5161, TMC5160, TMC2209, TMC2225, TMC2208, TMC2130, ST820, LV8729, DRV8825, A4988
• Driver interfaces: X, Y, Z0,Z1, E0, E1,E2 – 6 drivers, 7 motor outputs
• Control of 3 MOSFET transistors for heating up to 3 extruders – HEAT0, HEAT1, HEAT2, led out to screw terminals
• Control of 1 MOSFET for bed heating, up to 20A.
• Fan outputs on terminal, PWM control
• Slot for SD card

BIGTREETECH SKR PRO V1.1 is a motherboard designed for controlling 3D printers WITHOUT an additional adapter board. The board is optimized for building small to large 3D printers with extended functionality and up to 3 extruders. It is built on the STM32F407ZGT6 microcontroller, with a clock speed of 168MHz, 1024kB flash and 192kB SRAM memory. Numerous signals for controlling the 3D printer are led out on socket and pin headers. The board supports 6 stepper motor drivers (X, Y, Z, E0, E1, E2) with dedicated output pins for the motors. Depending on the configuration, a second Z motor can be used or an output for a third extruder. The STEP, DIR, ENA signals can be taken from pin headers when using external drivers. Headers are provided for endstops, along with filter circuits for proper triggering. Connectors for standard LCD screens and touch screens are provided. Screw terminals are available for connecting 3 heaters - 3 extruders. Power supply and voltage supply for bed heating are led out on a separate power terminal. 4 thermistor inputs are led out on headers to control temperatures. The board features numerous standard 2-pin connectors for connecting fans, some with PWM control. Miniature LEDs allow checking activated outputs – heaters and fans, presence of supply voltage, and triggering of endstops. A RESET button is available for restarting the microcontroller board. In addition to the USB-B port for control, a USB-A port for flash memory is also available.

The following can be noted as extended functions:

· Connection of SD card for firmware update or printing from it

· Additional USB-A port for printing from flash memory

· Connector for connecting a wireless wifi module – ESP01S

· Communication connectors – SPI, I2C, UART,

· Connectors for PWM, analog and other signals

Power supply for BIGTREETECH SKR PRO V1.1 is via the USB connector or from the screw terminals, selectable via a jumper. The screw terminal power supply is 12-24V.

Multiple signals are led out on all headers, each of which can be seen on the bottom layer of the board, printed in white.

Advantages of BIGTREETECH SKR PRO V1.1 compared to solutions based on RAMPS boards:

• High performance, ability to build a large printer with a powerful heated bed and 3 extruders
• Higher travel speed – thanks to the higher clock speed of the microcontroller (168MHz) more frequent pulses are possible for the STEP pins of the drivers.
• Ability to connect to a wifi network
• Ability to connect screens
• Filtered inputs for endstops, multiple endstops
• Additional connector for a second Z motor, additional driver for a third extruder
• High heated bed power: up to 360W

Additional information:

• User Manual
• GitHub page with descriptions, schematics, hardware, firmware, software
• First Steps