BIG-DIPPER

Introduction

BIG-DIPPER is a combination of Duet3 mini5+ and Mini 2+. It's based on ATSAME54P20A and pin assignments are exactly the same as those of mini5+, so the mini5+ firmware can be used directly.

Compare to mini5+, the power supply and IO protection have been upgraded to a certain extent to make them safer. And you can switch between the WIFI version and the Ethernet version by replacing the module. WIFI version module supports external antennas.

Based on the good ecology of the RRF firmware and on-board 7-axis (7xTMC2209), the board can be easily configured in a variety of 3D printer models, such as VORON series, multi-Z-axis models, double-X models etc.

• Compatible RepRapFirmware versions: RRF 3.2 and later

For firmware update instructions, see Installing and updating firmware.
If running from an SBC, see SBC setup for Duet 3.

Warnings

• Never connect or disconnect anything to your Big Dipper when there is power applied to it! Exception: you may connect or disconnect the USB cable with power applied, but see the important notes on using a USB connection.
• Take great care to connect the + and - leads from the power supply the right way round to the VIN terminal block!
• Do not exceed 25V VIN input voltage!
• When the stepper motors are connected to the Big Dipper, do not move any parts by hand that make the motors rotate rapidly! For example, if you need to move the print head by hand, or the carriages of a delta printer by hand, do it s-l-o-w-l-y. Likewise, if you need to rotate the extruder gear by hand, do it slowly. Rapid rotation of the stepper drivers will generate enough voltage to power them up in an uncontrolled fashion, and could generate enough to exceed their rated voltage.
• Do not insert an SD extender cable into the built-in SD card socket! These cables frequently damage the contacts inside the SD card socket. Even when they don't, they do not work well at the high SD card transfer speeds used by the Duet.
• When mounting the Big Dipper, if you use metal screws then make sure that they don't touch any of the electronic components or solder pads on the Big Dipper! Use the Nylon washers supplied with your Big Dipper under the screw heads.
• Be very careful if you use a multimeter to measure voltages on the board, especially on the fan connectors! The probes may slip and short against each other or to other components. If you short the two pins of a fan connector together, you will damage your Big Dipper.
• Do not rely solely on the Big Dipper electronics and firmware to guard against excessive temperatures in your 3D printer! Despite the advanced protection features in Duet firmware, electronics and firmware can fail in unexpected ways.
• If you use a USB connection to the Duet, take care to mitigate the effect of ground loops!

  
  

  Package contents

1 x Big Dipper (WiFi or Ethernet)

7 x Heat Sink

1 x Single Board Computer (SBC) ribbon cable

1 x External antenna with Extension cord (WiFi version only)

Stand alone mode vs SBC mode

The Big-Dipper is basically the same as the Duet3 Mini 5+.It is either be directly connected to a network, or to connect to a Single Board Computer (SBC) like a Raspberry Pi.

All standard printer functions, different kinematics, the network UI (DuetWebControl) etc work in stand alone mode.

SBC mode allows part of the functionality to be handled by the SBC. For example an HDMI or Pi touch screen can be used as the UI, The Pi can act as the network server and plugins for Duet Software Framework on the Pi allow for adding custom features for more advanced control and monitoring.

Features

1. Compact size: 148.5 x 87mm
2. Base on SAME54P20(ARM Cortex M4 @120Mhz)， fully compatible with Duet3 Mini5+
3. Onboard 7 TMC2209 stepper motor drivers
4. Input and output IO full TVS protection
5. 28V maximum input, 12V@2A DC-DC (12V fan power supply), 5V@8A DC-DC (power supply for Raspberry Pi and the system), two 3.3V@0.6A LDO (power supply for MCU and 3.3V peripherals respectively)
6. Two car fuses for hot bed input and main power input
7. Using XH2.54 connector, each interface function is exactly the same as mini5+
8. 7x PWM power MOSFET output（ 1 for heatbed, 2 for hot end, 4 for fans ）
9. RepRap Discount Smart Controller compatible sockets ，EXP1 and EXP2。Support monochrome displays such as 2004 ，12864。
10. UART1-Raspberry Pi pin header (including 5V@5A power supply)
11. Onboard TF card slot
12. Type-C USB socket
13. 3 Thermistor/PT1000 inputs and support for 2 PT100 or thermocouple inputs via the optional daughterboards.
14. Both Wifi and Ethernet versions
15. CAN bus that supports the next generation of Duet3D expansion boards, smart tools and

custom addons.

16. Set up your printer and update the firmware through the web interface.
17. All common 3D printer geometries are supported
18. Support for a wide range of Z probes including DC42’s IR Z probe and the Duet3D Smart Effector for delta printers.

Hardware Specification

Physical properties

Dimensions

Mounting

The form factor of the Big Dipper is the same as the Duet 2 WiFi/Ethernet and can be mounted in much the same way, though the driver connectors are flipped sides compared to the Duet 2 WiFi/Ethernet.

Cooling

In many applications passive cooling will be sufficient, especially if the board is mounted vertically in a well ventilated position. If active cooling is needed then a fan blowing across the back of the board along the line of the stepper drivers is recommended.

The stepper drivers' heatsinks are connected to the PCB and the majority of the heat is dissipated via the PCB so heatsinks on the stepper driver chips are largely ineffective.

MCU Temp

Unfortunately the SAME54P20A chip used in the Big Dipper does not have a functioning temperature sensor. In theory it does have an on-chip temperature sensor, but the errata document for the chip says it doesn't work. However, it has been enabled in RRF 3.3 as an experiment, and does appear to give useful readings on the samples tested.

Stepper Driver Temp

Due to this you would be unable to monitor the MCU temp in order to control fans. The driver sensors do work for fan control, but only return flags of warning and overtemp,

3D Model

The STEP files for boards are available on Github here.

Physical connections

Wiring diagram

Description of Connections

Notes

1. Total 12V load should not exceed 800mA
2. 5V can be powered from multiple inputs (USB, External 5V input, SBC) as well as the internal 5V regulator. Total 5V load should not exceed 800mA when powered from the internal 5V regulator. see the "Power distribution, 5V" section below for more information

LED indications

LEDs are provided to indicate the following:

The red LED next to the TYPE-C USB is "STATUS". It indicates the state of the board, as follows.

Pin names

For more information on pin names, see Pin Names.

RepRapFirmware 3 uses pin names for user-accessible pins, rather than pin numbers, to communicate with individual pins on the PCB. In RRF 3 no user-accessible pins are defined at startup by default. Pins can be defined for use by a number of gcode commands, eg M574, M558, M950.

The Duet 3 series uses the pin name format "expansion-board-address.pin-name" to identify pins on expansion board, where expansion-board-address is the numeric CAN address of the board. A pin name that does not start with a sequence of decimal digits followed by a period, or that starts with "0." refers to a pin on the Big Dipper.

Input/Output

OUT headers

OUT_0 to OUT_6 are all PWM-capable. OUT_6 is shared with LASER/VFD. See tables above for notes on voltage selection and current limits.

IO headers

There are 7 IO headers on board. IO_0 to IO_4 have pins for input, output, 3.3V, 5V and Gnd supplied. IO_5 and IO_6 have an input, 3.3V and Gnd supplied. This enables support for a wide range of endstops, probes, filament monitors and future low bandwidth devices. RepRapFirmware 3 can be configured to map these ports to the appropriate functions as required.

Except as noted in the table below, an IO_x_IN pin can always be used to provide a digital input (e.g. for endstop inputs or filament monitors), and an IO_x_OUT pin can always be used to provide a digital output.

IO output pins can be used as inputs, but are only 3.3V tolerant. IO input pins can be used as outputs, but have 10K protection resistors in series with them, so you would need to bypass these to use them as outputs. On board revision v1.01 and later only, jumpers allow the 10K resistors on IO2.in and IO3.in to be bypassed with 470R resistors. This is required to use IO2 or IO3 for I2C.

The individual IO_x connectors have the following capabilities:

Power distribution

VIN (Input voltage from PSU)

Supply 12V-24V input power (11-25V absolute minimum/maximum) between the GND and VIN terminals.

VIN is split via two fuses:

V_FUSED: 20A : All on board power demands, other than OUT0 (Normally used for heated bed

OUT0_FUSE: 15A: Directly to the V_OUT0 terminal

VFUSED is distributed across the board as follows:

• 12V Regulator
• 5V regulator
• Stepper drivers (including external driver header)
• OUT 1 and OUT 2 headers
• V_OUTLC1 and V_OUTLC2 selection jumpers

12V

12V_EXT: 1500mA limit, Supplied to:

• V_OUTLC1/2 for OUT_3 thru OUT_6.
• 12V header (useful for supplying 12V to a VFD controlled from the adjacent 5V PWM header)

5V

5V: Split up to 5V_EXT, 5V_INT. Those points can also be supplied by VBUS (i.e. USB) and from the 5V_SELECT jumper that selects between 5V_EXT_INPUT and 5V_SBC. (see 5V power options below for more details).

• 5V_EXT feeds

  
  

• • IO headers
  • 12864 display and PanelDue
  • LASER/VFD header
• 5V_INT feeds
• Internal and External 3.3V regulators

  
  

• • External Driver header
• Internal 5V logic

5V input can come from one of these sources:

• Onboard 5V regulator: Once 3.3V and other onboard demands are met approximately 700mA remains for use on the 5V_EXT rail.
• USB: Can supply both 5V_INT and 5V_EXT. limits based on USB specification.
• 5V_EXT_INPUT: With the 5V_SELECT jumper set to this position, 5V is passed through to both 5V_EXT and 5V_INT from the EXT_5V header. When using EXT_5V, add jumper to Int_5V_Disable, to disable the onboard 5V regulator. The EXT_5V header also has a pin for controlling an external power supply (note signal shared with io4.out). This allows for the board to be powered from 5V, with an external supply for VIN turned on and off as required.
• 5V_SBC: In some, limited, cases it may be desirable to power the board from the 5V output of a SBC connected to the SBC header. Note that the total power of the Duet+ peripherals must be factored into the SBC power budget. Also note that powering the SBC from the duet is not supported.

3.3V

3.3V: Internal 3.3V supply for onboard logic, Temperature Daughterboards and external drivers

• 3.3V_EXT
• • IO Headers
  • External SD cards

Connecting Displays

Connecting a 12864 display

The signal levels are mostly 3.3V. This means that LCD modules using a ST7920 display powered from 5V (e.g. the RepRapDiscount display) will not work reliably. Use a display with a ST7567 controller instead. The display we test with is the Fysetc Mini 12864 display version 2.1. You can connect this directly to the EXP1 and EXP2 connectors using the straight-through ribbon cables normally supplied with this display. Enable the display using these commands in config.g:

M918 P2                     ; enable ST7567-based 12864 display
M150 X2 R255 U255 B255 S3   ; set all 3 LEDs to white

Copy

You can adjust the M150 command to change the backlight colours. Please note, interrupts are disabled for a short time while the backlight colours are changed, and printing will be paused during this time; therefore you should not change the backlight colours during a print.

Connecting a PanelDue

A PanelDue can be connected to IO_0 using a 4-wire cable. See Connecting a PanelDue

Alternatively, it can be connected using a ribbon cable plugged into the socket labelled PanelDue_SD, which enables access to the PanelDue SD card socket. However, there are some caveats:

• The PanelDue connector shares the io0.out and io0.in pins, so IO_0 cannot be used at the same time.
• Duet 3 boards support the card detect signal. Newer versions of the PanelDue 5i and 7i (v1.01 and later of the 5i and v2.01 and later of the 7i) provide this signal, but older versions will need to be modified. See Connecting a PanelDue

Connecting a Raspberry Pi

The Big Dipper cannot power the Pi. You must power the Pi separately. The Raspberry Pi is sensitive to the input voltage, and many smartphone chargers or other USB power supplies cannot supply sufficient voltage. Therefore, we strongly recommend that you use the official Raspberry Pi PSU, or another PSU specifically designed to power a Raspberry Pi. If the red LED on the Pi is not continuously illuminated, the power supply is insufficient.

In other respects, SBC connection to the Big Dipper and configuration is the same for the Duet 3 Mini as for the Duet 3 Mainboard 6HC. See SBC Setup for Duet 3.

When using an attached Raspberry Pi or other SBC, the WiFi or Ethernet interface on the Big Dipper is disabled.

Connecting Stepper Motors

See Connecting stepper motors.

Connecting Fans

See Connecting and configuring fans.

Attachments

• Schematic files
• Pinout File

For more documents including configuration information, please check https://github.com/FYSETC/FYSETC-BIG_DIPPER

Support

Fysetc Discord Server

Shop

Fysetc Offical Store

Updated on: 01/07/2026