The Duet is a 123mm x 100mm all-in-one 3D printer control board. The original Version 0.6 was a 4-channel board with the following main features:
- ATSAM3X8E processor (ARM Cortex-M3 core) running at 84MHz, with on-chip Ethernet and USB
- Four A4982 stepper motor drivers, supporting fixed 1/16 microstepping. Full, half and quarter microstepping can be set by solder bridges on the board, but software control of microstepping is not supported.
- The A4982 is similar to the popular A4988, but the package variant used in the Duet has better thermal characteristics than the A4988, so it can be used at slightly higher currents.
- I2C Digital potentiometer for control of stepper motor currents
- Power mosfets to drive heated bed, one hot ends and a controllable cooling fan
- Two thermistor inputs for heated bed and hot end
- Four endstop channels for X, Y, Z, and E0
- SD card socket SD 2.0 compliant
- 10/100T Ethernet port for network control via an on-board web server
- Micro-USB port
- Expansion connector to allow connection of extensions and daughter boards, such as the DuetX4 expansion board, the RepRapPro additional hot end shield, and the PanelDue LCD touch-screen controller.
- Input voltage range 12V to 35V (tested to 24V)
- Optional switching regulator to provide 5V supply, and linear regulator to provide 3.3V supply from the 5V supply
- Similar architecture to the Arduino Due
The current Version 0.8.5 of the Duet adds the following additional features:
- A second extruder channel (E1).
- A second PWM fan output.
- E1 motor current controlled by the SAM3X8E DAC0 channel.
- Two "always on" fan pins.
- Dedicated header for the PanelDue.
- Dedicated probe header, supports many different probes including David Crocker's mini IR probe.
- Additional pins accessed on the SAM3X8E processor to enable the new features.
Version 0.8.5 also features the following improvements:
- Lower noise components and circuit layout used for the 5V BUCK circuit.
- Complete ground plane - reduce noise and potential ground loops.
- Switches and power indication LEDS moved to the same edge as the SD/USB/Ethernet for simpler access and indication.
- VSSA now present on the expansion header. This combined with the changes to the Duex4 0.2a mean that analogue ground is now used for all 7 temperature measurement channels.
The Duet hardware design is licensed under the CERN OHW License 1.2: the design is free to be distributed and modified within the terms of this license. All the design files are available on Github. The Duet was completely designed using the Open Source software package KiCAD so hacking and building on this design is accessible to all. Pins/output references correspond to the references used for Arduino Due.