Duet 2 WiFi/Ethernet Hardware Overview

The Duet 2 Wifi and Ethernet are 2nd generation Duet 3D printer electronics. The main hardware features are listed below.

^{The feature diagram for V1.03 and earlier is below}

• Compatible RepRapFirmware versions: RRF 2.x, RRF 3.x
• The Duet 2 WiFi has a WiFi module, the ESP8266. This is another 32-bit microcontroller with its own flash storage area, which is where the WiFi connection details are stored. It runs its own firmware, which occasionally needs to be updated. The Duet 2 Ethernet has a W5500 TCP IP processor on board which handles the low level Ethernet networking functions. Installation of both the Wifi and Ethernet modules on the same board at the same time is not supported.

Note: At high currents, it is essential to use either ferrules or solid core wire with the terminal blocks on the Duet 2 and DueX.

Importantly Duets are Open:

• The Duets are Open Hardware, https://github.com/T3P3/Duet/blob/master...
• All hardware source files are available on Github.
• Both the Duet Web Control web interface and RepRapFirmware are Open Source Software http://www.gnu.org/licenses/gpl-3.0.en.h... with source files available and actively maintained, see Contributing to firmware development for more information.
• The Duet hardware and RepRapFirmware are built with Open tools: designed in http://kicad-pcb.org/ and https://eclipse.org/: using open tools means the barrier to getting involved is as low as possible.

For wiring and pinout of the board, see Duet 2 WiFi and Ethernet wiring diagrams.

Duet 2 WiFi and Ethernet boards have four 4mm clearance holes at the corners of the board. You can use M4 screws to attach the board to a panel or an enclosure. The hole patterns / mounting centres are 115mm x 92mm, full dimensions are shown in the diagrams:

Duet 2 Wifi Dimensions

Note: from v1.05 the Wifi Antenna size on the Duet 2 Wifi internal antenna version has increased slightly

Duet 2 Ethernet Dimensions

Note: the change from 1.04 to 1.05 has no impact on Duet 2 Ethernet

The diagrams show the mounting hole points in the format X,Y so the bottom left hole is at X=4mm, Y=4mm, the top left is at X=4mm, Y=119mm and so on. The board has 3 additional 2.54mm holes at: (53.1,9.1),(56.7,28.7),(81.5,22.) for mounting the Ethernet Module.

On Duet 2 WiFi and Ethernet production boards, the holes are isolated and not plated through. On pre-production Duet 2 Wifi boards, the mounting holes are plated-through and connected to the ground plane.

Please note:

• If you mount the board on a metal surface, use standoffs to ensure that the back of the board cannot short against the plate. A minimum standoff length of 5mm is advised, however larger is preferred for better cooling.
• Do not use metal washers under the mounting screws, or screws with large heads (e.g. button head). Nylon washers are recommended. With a metal washer there is a risk of creating a short between the E1 HEAT LED and ground.

The PCB is designed to transfer heat from the stepper drivers and power mosfets to the underside of the board. Therefore your mounting method should encourage good airflow underneath the board.

If you mount the board vertically, make sure that cool air can enter at the bottom of the board, flow upwards behind the board, and escape at the top. Convection cooling will usually be sufficient, but if you are using high stepper motor currents then you may wish to add a fan below the board to encourage the upward flow of air. Make the spacing between the back of the board and the panel or enclosure large enough to allow a good flow of air.

If you mount the board horizontally then a cooling fan is recommended, especially if there are other heat-generating components in the vicinity such as power supplies, SSRs or stepper motors. Position the fan to blow air underneath the board (preferably along the top as well), especially along the row of stepper driver chips and between the power input and bed heater terminal blocks.

Important! The higher the motor currents you set, the more important it is to cool the board. Always use a cooling fan if you run a Duet 2 Wifi or Duet 2 Ethernet above 2.0A motor current.

Phil Maddox has created a 3d model of the Duet 2 Wifi hosted here:

https://grabcad.com/library/duet-wifi-1

Giuliano Moschini has created a model based on the Duet 2 WiFi model for the Duet 2 Ethernet:

https://grabcad.com/library/duet-etherne...

The Duex CAD file is here, thanks to Morten Nielsen for making this version:

https://grabcad.com/library/duex5-1

The boards all support connection to a computer over USB, using any standard 3D printer host control program. The Duet 2 WiFi can also connect to a secure WiFi network, while the Duet 2 Ethernet, Duet 0.8.5 and 0.6 have an Ethernet port. The primary way to control these boards is with a web interface controlled through the network. Although they have removable on-board SD cards, the network interfaces provide fast enough file transfer that it is generally preferable never to remove the on-board SD card.

The boards also support a colour touchscreen called the PanelDue.

See also:

• Getting connected to the Duet

The Duet boards run on two basic power circuits. The digital electronics are supplied by a 5V circuit, which is internally converted down to the 3.3V levels that drive the MCU. This circuit also drives all the LEDs and sensors, and can be configured to feed the fans. The high-power devices, specifically the stepper motors and the heaters, are powered by a higher voltage, typically 12 or 24 V. This 12/24V circuit can be switched on and off through the PS_ON pin, if the power supply supports this (it may be a good idea to add such support through a relay, for safety reasons, if it doesn't) without interfering with the MCU at all. Alternatively, the Duet boards can draw power from this circuit to power the 5V circuit.

From Version 1.04 onwards the Duet 2 is fitted with 3 blade fuses:

• 1A for the VIN going to the fans
• 7.5A for the VIN going to the heaters and stepper motors
• 15A for the VIN going to the Bed heater

See also:

• Mounting and cooling the Duet
• Power Wiring

The Duet 2 (WiFi and Ethernet) can drive 5 independent stepper motors. It uses Trinamic TMC2660 stepper drivers, which in addition to the standard step/direction/enable interface provide additional functionality (for example digital current selection and interpolation between microsteps) through SPI. If these chips become damaged or if users wish to use different drivers (for example supporting higher currents) then 5 additional channels of step/direction/enable pins are available on the expansion connector. With the onboard stepper drivers, it is possible to connect multiple motors in series; a connector is provided to make this convenient for the Z axis.

The Duet 2 (WiFi and Ethernet) provides connectors for one endstop for each axis; these can be simple microswitches (normally open or normally closed) or they can be more complicated boards (for example optical switches) so long as they run off 3.3 V and can provide a digital (on/off) output. Additional endstop pins are available on the expansion connector. Any of these endstop pins can also be configured to trigger user-defined actions, for example as a filament-out sensor or emergency-stop button.

The Duet 2 (WiFi and Ethernet) also provides a connector specifically for a Z probe. This supports simple switches, boards producing analog outputs (at 3.3 V levels) and boards providing analog outputs that require an on/off modulation signal.

See also:

• Choosing and connecting stepper motors
• Connecting endstop switches
• Connecting an Emergency Stop button
• Connecting and configuring filament-out sensors

The Duet 2 (WiFi and Ethernet) supports power distribution to and control of three heaters: a heated bed (assumed to be the highest current draw with a maximum of 18A) and two extruder heaters. These are fed from the 12/24V circuit, but the PWM switching is carried out by MOSFETs on the ground, so if necessary they can be run off different voltages. Very high power bed heaters should probably be supplied independently and switched with a SSR.

Alongside each heater there is a temperature sensor input. These can be connected directly to thermistors (whose properties are set in the printer configuration files) or via expansion boards to PT100 sensors or thermocouples.

The Duet 2 (WiFi and Ethernet) also provides connectors for several fans, some always-on and some PWM-controlled. These can be supplied with 12/24V or with 5V, or (since again the switching is by MOSFETs on the ground line) if necessary from user-supplied power inputs.

See also:

• Connecting thermistors or PT1000 temperature sensors
• Connecting thermocouples
• Connecting PT100 temperature sensors
• Choosing and connecting a bed heater
• Connecting and configuring a chamber heater
• Connecting extruder heaters
• Connecting and configuring fans

The MCU driving the Duet boards has considerably more inputs and outputs than are used on the main board. Many additional lines are available on an expansion connector.

For the Duet2 the Duex 2 and Duex 5 expansion boards add 2 and 5 extra channels respectively. There are 2 more channels available on the CONN_LCD header, giving a total of 12 stepper channels.

For the Duet 0.6 and 0.8.5 the Duex 4 provides 4 additional stepper drivers, endstop connectors, heater outputs, and temperature inputs.

See the Duet 2 WiFi and Ethernet wiring diagrams for the expansion connector pinout.

When on external 5V power with no connected devices drawing power from the 3.3V or 5V supplies, both the Duet 2 WiFi and Ethernet draw about 200mA average from the 5V supply with the network interface enabled. For the Duet 2 WiFi, the peak current when transmitting may be in excess of 300mA.

The board has a number of on board LEDs which are used to indicate the state of power, endstop switches, heaters etc:

The Duet 2 Wifi and Duet 2 Ethernet both use the same Duet 2 base controller board. The difference is only in the communications module. This base controller board has gone through a number of PCB design revisions. The revision number is marked on the silkscreen on the board, to the left of the large processor chip. the linked page has more information on the Version Numbering system.

On the Duet 2 Wifi internal and external antenna versions the wifi module changed to an Espressif ESP-WROOM-02D (internal) or 02U (external) module. On the Duet 2 Wifi internal antenna version this change means the size of the internal antenna that projects past the end of the board has increased slightly. See the dimensions section above.

Further minor component value change/tweaks to improve 5V regulator and EMI performance.

Compared to PCB revision v1.03 the following changes have been implemented:

• Provision of a miniblade fuse for the Motors and heaters - Supplied with a 7.5A fuse
• Provision of a miniblade fuse for the Heatbed - Supplied with a 15A fuse.
• The Z probe input improved to tolerate inputs up to 30V.
• The endstop inputs will tolerate at least 8V.
• Replaced erase switch with an erase jumper
• Changes to some layouts, and trace routing to further improve EMI performance.
• On 1.04a and later the JTAG header is removed

Source files: https://github.com/T3P3/Duet/tree/master...

Note: 1.04 Duet WiFi/Ethernet boards manufactured in June/July 2018 had the incorrect resistor value fitted at position R107 (10K instead of 100R). On these boards, the external reset pin on the expansion connector will not work. This can be remedied by soldering a 100R 0603 resistor on top of the existing one at position R107.

The feature diagram for PCB revision v1.03 and earlier is below

Compared to PCB revision v1.02 the following changes have been implemented:

• The Fan MOSFETS now have a miniblade fuse in the VIN supply (not 5V supply).
• Each of the TMC2660s Stall Guard outputs is ORd together and fed to the MCU. This allows for quicker reaction to SG signals.
• Minor routing changes

Source files: https://github.com/T3P3/Duet/tree/master...

Compared to PCB revision v1.01 it had the following changes:

• Changed to a resettable VSSA fuse. Now if the thermistor inputs are connected to VIN, the VSSA fuse should reset rather than needing to be replaced.
• Added capacitors on stepper driver outputs to reduce EMI and improve protection against inductive transients.
• Added flyback diodes to the PWM fan outputs to protect against non brushless DC fans/pumps.
• Minor routing changes.

Source files: https://github.com/T3P3/Duet/tree/master...

Compared to PCB revision v1.0 it had the following changes:

• Minor routing changes
• The filter capacitors for the ADC inputs are connected to main ground, to better protect the MCU if the VSSA fuse blows

Source files: https://github.com/T3P3/Duet/tree/master...

The first production version. Compared to the prototype it had the following changes:

• ESP_COMMS Header breaks out all the spare ESP pins.
• Added test points for Step,Dir and CS for the onboard stepper drivers.
• Top and bottom copper layer thicknesses increased to 2oz
• Added a global enable signal for the TMC2660 drivers
• Minor routing changes.

Source files: https://github.com/T3P3/Duet/tree/master...

This board is identifiable by the white solder-mask (all other boards are blue) it was made in a limited production run compared the version.

1st generation Duets are now obsolete hardware, however they are still supported in RepRapFirmware using the 1.x releases. In future new features of RepRapFirmware may not be implemented for 1st generation Duets due to their more limited capability.

An updated and expanded version of the Duet 0.6, called the Duet 0.8.5 (multiple unreleased versions came in between) was released in Aug 2015.

More details are available of the RepRap wiki here:

http://reprap.org/wiki/Duet

The source files are here

https://github.com/T3P3/Duet/tree/master...

The first duet released was version 0.6, developed by Think3dPrint3d and RepRapPro in 2013. More details are available on the RepRap Wiki:

http://reprap.org/wiki/Duet#Duet_v0.6

The source files are here:

https://github.com/T3P3/Duet/tree/master...

The Duet 2 WiFi and Duet 2 Ethernet provide the following hardware improvements over the Duet 0.8.5:

• 120MHz ARM Cortex M4 processor (ATSAM4E8E) with 128Kb RAM and hardware floating point unit, instead of 84MHz M3 (ATSAM3X8E) with 96Kb RAM as on the Duet 0.8.5
• On the Duet 2 WiFi only, WiFi connection instead of wired Ethernet, supporting typically 1Mbyte/sec file upload speed with a good wireless network connection and suitable SD card
• TMC2660 stepper drivers instead of A4982. These drivers support higher motor current and up to 256x microstepping, with optional 16x interpolation from 16x to x256.
• Variable microstepping
• The maximum recommended supply voltage, VIN , is 25V (reduced from 30V) due to the new driver chips
• Auto ADC calibration
• Three controllable fans instead of two
• Fans can be powered from VIN , from +5V, or using external power supplied through the centre pin of the VIN /5V selector block
• Higher bed heater circuit current rating (18A)
• Support for thermocouple and PT100 daughter boards
• Connector for a second Z motor
• Supply voltage monitoring, facilitating print resume-after-power-fail function
• Larger terminal blocks for the extruder heater outputs, to make wiring easier
• Diagnostic LED
• Support for up to five additional heaters and stepper drivers on the expansion bus, instead of four, plus another two additional external stepper drivers to give a total of 12 stepper drivers maximum
• Other design changes to increase board resilience, improve safety, and reduce EMI

See the Duet family of motion control electronics page for a feature comparison table between different versions of the Duet 2.

• The Duex 4 expansion board that was made to go with the Duet 0.6 and 0.8.5 is not compatible with the Duet 2 WiFi. Use the Duex 2 or Duex 5 instead.
• The maximum recommended power input voltage is 25V. This is a permanent limitation, because the TMC2660 drivers are rated at 30V when supplying power to motors.
• On the white pre-production boards in some wiring configurations, if you reset the Duet 2 WiFi by pressing the Reset button when the motors are energised, then the stepper motors may move while the Reset button is held down. This is fixed in the production boards.