The Duet 3 Mini 5+ balances value and performance, focused on small and medium size machines that do not need the high power output of the Duet 3 Mainboard 6HC. It provides 5 on board drivers and the normal complement of heaters, fans, IO, LCD etc. There are Wifi and Ethernet variants, with the option of using an SBC (Single Board Computer, e.g. Raspberry Pi) for control in the same manner as other Duet 3 mainboards. It has a header for a two driver expansion board and a CAN-FD port for connecting Duet 3 expansion and tool boards.

Except where otherwise stated, the following applies to both the WiFi and Ethernet versions.

The main hardware features of the Duet 3 Mini 5+ are listed below.

• Compatible RepRapFirmware versions: RRF 3.2 and later

For firmware update instructions, see Duet 3 Mini 5+ firmware page. If running from an SBC, see Update Duet 3 connected to SBC.

See the Duet family of motion control electronics page for a feature comparison table between different versions of the Duet.

The form factor of the Duet 3 Mini 5+ is the same as the Duet Maestro and can be mounted in much the same way, though the driver connectors are flipped sides compared to the Maestro.

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.

Unfortunately the SAME54P20A chip used in the Duet 3 Mini 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.

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,

The STEP files for both boards are available on Github here:

https://github.com/Duet3D/Duet3-Mini5plu...

See: Duet 3 Mini 5plus Wiring

See: Duet 3 Mini 5plus Wiring. The wiring page also includes a description of each connection.

A list of LEDs on the PCB and their meaning is on the Duet 3 Mini 5plus Wiring.

For pin names used by RepRapFirmware, see Duet 3 Mini 5plus Wiring.

OUT0 to OUT6 are all PWM-capable. OUT6 is shared with LASER/VFD.

Capabilities of IO_0 to IO_6 are shown below.

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

VIN is split via two fuses:

V_FUSED: 10A : 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 OUT2 headers
• V_OUTLC1 and V_OUTLC2 selection jumpers

There are 4 on board power rails, generated wither directly or indirectly from V_FUSED

• 12V_EXT: 800mA 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: 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
• +3.3V: Internal 3.3V supply for onboard logic, Temperature Daughterboards and external drivers
• 3.3V_EXT:
  • IO Headers
  • External SD cards

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.

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

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.

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

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; see Connecting an LCD control panel

Unlike the Duet 3 MB6HC, the Duet 3 Mini 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 Duet and configuration is the same for the Duet 3 Mini as for the Duet 3 MB6HC. See SBC Setup for Duet 3.

When using an attached Raspberry Pi or other SBC, the WiFi or Ethernet interface on the Duet 3 Mini is disabled.

See Choosing and connecting stepper motors.

See Connecting and configuring fans.

• Added Jumpers to bypass 10K input protection resistors with 470R resistors for IO2.in and IO3.in. This is to allow these inputs to be used with I2C.
• Add a 10K pulldown resistor between signal line io4_out and ground. This is to prevent PS_ON turning on momentarily when the board is powered up.

• Component footprint and solder stencil changes to improve manufacturability
• Ground plane changes to further improve EMC performance
• Minor component changes to increase commonality with other Duet 3 products

• Add 5V TVS diode footprint option so either 1610 or SMC can be used on 5V.
• Move OUT3 and OUT 4 connector up slightly to clear the stepper diver expansion header.
• Added pullup between Driver enable and 3.3.V
• Add 3.3V TVS diode
• Updated the 12V and 5V BUCK input circuits to improve EMC performance.
• Updated the passive components around the Ethernet Phy to improve EMC performance.
• Further minor routing and component updates.

• Added CAN support
• Removed IO_4 (pins used for CAN) and renamed IO_5, 6,7 to 4,5,6.
• Remove 1 stepper driver and TMC diag mux. Used freed pins to route each stepper driver diag line directly to the MCU. Significantly improves stall detection performance.
• Swap 4 wire fan pin headers for normal molex KK
• 3 way jumper to choose between External 5V and 5V_SBC
• Swap the pinout for IO6 and IO7 to be the same as Duet 2
• Rename DIAG LED to STATUS
• Further minor routing and component updates.

First prototype, this revision will not be supported in future firmware releases.