Duet Hardware Overview

Features ¶

The main hardware features of the 2nd Generation Duets (Wifi and Ethernet) are listed below

Duet Wifi ¶

Powerful 32 Bit Processor: Atmel SAM4E8E: 120MHz ARM Cortex-M4 microcontroller with floating point unit, 512Kb flash memory, 128Kb RAM and many peripherals.
Dedicated Wifi module: Low level networking is handled by a separate module, this leaves the main processor free to do precise stepper pulse timing and implement other advanced features.
Super quiet TMC2660 stepper drivers: SPI controlled and capable of up to 256 microstepping with optional 16x interpolation when using 16x microstepping. Hardware support for variable microstepping and variable stepper current for optimum speed and power efficiency.
On board High speed SD card and support for a second SD external card if required.
Dual extruders: 3 heater/thermistor channels for a heated bed and 2 extruders.
3 PWM controllable and 2 always-on fans. These can be run from either the input voltage, from 5V, or from external power for added flexibility.
High Power rating: Each stepper driver is capable of 2.8A motor current, currently limited in software to 2.4A. The bed heater channel is specifically designed for high current (18A)
Connect via PC, tablet or smartphone on the same network to the Duet Web Control web interface. There is no need for an app install, internet connectivity or cloud service to sign up for yet you can control your printer, upload and start prints from the browser.
Setup your printer and update the firmware through the web interface. No need to compile your own firmware.
Also connect via USB or serial if desired.
The Duet Wifi uses WPA-2 encryption for network security. The DuetWifi does not need to be connected to the internet - keep it on a local network for added security.
Most printers supported: All common 3D printer geometries are supported, with easily modified configuration templates for popular designs. Along with 3D printers a wide variety of CNC machines and lasercutters can be controlled.
Expandable up to 7 extruders: Support for a further 5 stepper drivers and heaters on the expansion header. The Duex2 and Duex5 expansion boards are available.
Firmware support for mixing nozzles and remapping axes to use high power external drivers.
Touch Screen support for the PanelDue controller provides a full colour graphic touch screen controller with virtual keyboard. Also talks G-code for maximum flexibility.
Advanced Calibration Support: Use an optional add-on of DC42’s highly repeatable contactless IR probe combined with advanced firmware features for more accurate printer calibration. Many other probe types are also supported.
Automatic ADC gain calibration for thermistors allows for accurate and repeatable temperature setting. In addition PT100and Thermocouples are supported through new SPI daughter boards.
Power monitoring to allow for state save on power fail.
Beta support for the Duet3d Filament Monitor both magnetic and laser versions.

Duet Ethernet ¶

The Duet Ethernet is identical to the Duet WiFi except that the WiFi module is replaced by an Ethernet module.

Importantly the Duet Wifi and Duet Ethernet are Open:

The Duet Wifi and Duet Ethernet 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 DuetWifi 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.

Wiring and pinout ¶

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

Microcontroller ¶

The Duet 2 (Wifi and Ethernet) family of boards are based on the 32-bit ARM microcontroller SAM4E8E. Its general abilities are:

CPU family: Cortex M4
Clock speed: 120 MHz
Flash space: 512 kb
RAM size: 128 kb
Operating voltage: 3.3 V
Floating-point: hardware (single precision)

The Duet WiFi additionally 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 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.

Connectivity ¶

The boards all support connection to a computer over USB, using any standard 3D printer host control program. The Duet WiFi can also connect to a secure WiFi network, while the Duet 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:

Power distribution ¶

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.

See also:

Motion ¶

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:

Heating ¶

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:

Expansion ¶

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 DuetWifi the Duex2 and Duex5 expansion boards add 2 and 5 extra channels respectively.

For the Duet 0.6 and 0.8.5 the DueX4 provides 4 additional stepper drivers, endstop connectors, heater outputs, and temperature inputs.

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

Electronics power consumption ¶

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

LED indications ¶

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

Version History ¶

2nd Generation Duets ¶

The Duet Wifi and Duet Ethernet both use the same base controller board. The difference is only in the communications module. This base controller board has gone through a number of minor revisions. The version number is marked on the silkscreen on the board, to the left of the large processor chip.

v1.03 ¶

Compared to v1.02 it had the following changes:

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...

v1.02 ¶

Compared to v1.01 it had the following changes:
Changed to a Resettable VSSA. Now if the thermistor inputs are connected to VIN the VSSA fuse should reset rahter than needing to be replaced
Added capacitors on stepper driver outputs to reduce EMI
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...

v1.01 ¶

Compared to 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...

v1.0 ¶

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...

prototype (v0.10) ¶

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 ¶

Duet 0.8.5 ¶

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...

Duet 0.6 ¶

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...

Hardware difference between Duet 2 and Duet 0.8.5 ¶

The Duet WiFi and Duet 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 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 RTD 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

Hardware limitations ¶

The DueX4 expansion board that was made to go with the Duet 0.6 and 0.8.5 is not compatible with the Duet WiFi. Use the DueX2 or DueX5 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 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.

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