¶ Introduction
The Duet 3 Expansion Mini 2XD is specifically designed for the expansion header of the Duet 3 Mini 5+. It may be possible to use it with other boards but this is not supported. It provides 2 external motor driver channels that match those on the Duet 3 6XD.
¶ Features
¶ Hardware specification
The main hardware features of the Duet 3 Expansion Mini 2XD are listed below.
| HARDWARE SPECIFICATION | |
|---|---|
| External Driver Support | 2 ports with step/direction/enable outputs, and fault inputs. Signalling is 5V single ended, active low. |
| Other I/O | NIL |
| Connection | Directly mounted on the Duet 3 Mini 5+ Mainboard. |
¶ Operating limits
| Input power voltage | 5V (provided by the Duet 3 Mini 5+ via the expansion header) |
| Fuses | No on board fuses, shared V_FUSED protection from Duet 3 Mini 5+ |
| Maximum ambient temperature | 70°C |
¶ Firmware notes
Compatible RepRapFirmware versions: RRF 3.6.1 and later on the Duet 3 Mini 5+ mainboard. Earlier firmware versions may provide correct motion but do not support the DRIVER_ERROR inputs. There is no firmware loaded on to the Duet 3 Expansion Mini 2XD itself.
The drivers are numbered "5" and "6" to reference them, for example to assign them as the X and Y axes:
M584 X5 Y6
Use M569 to set them up with appropriate timing chraracteristics for the external driver, for example:
M569 P5 T2:2:2:2
M569 P6 T2:2:2:2
¶ Physical properties
¶ Dimensions
¶ Mounting
The Duet 3 Expansion Mini 2XD has mounting standoff holes that align with matching holes on the Duet 3 Mini 5+.
These pictures show the Mini 2+ mounted but the procedure is the same of the Mini 2XD
Nylon standoffs are supplied with the Duet 3 Expansion Mini 2XD to mount it securely.
- 11mm tall for 1.6mm PCB with 2.5mm holes -e.g. FIX-MADA-11 or TRDLCBST-7-01
¶ Physical connections
¶ Wiring diagram
¶ Connecting External Motor Drivers
The Duet 3 Expansion Mini 2XD supports directly connecting external stepper drivers that have opto-isolated or similar inputs. Note that:
- The Step and Dir outputs from the 2XD are close to 0V when "on", and close to 5V when "off".
- The 2XD generates negative-going step pulses, and this will only work if the driver samples steps on the leading edge of the pulse. For stepstick and similar drivers, that will depend on the driver chip. Otherwise, add an inverter between the step output and the driver.
- Direction can be flipped using M569 S parameter.
- The Enable output is close to 0V when "on" and close to 5V when "off", or vice versa, depending on the position of the 'Driver Enable Polarity' (En_Pol) jumper. Note, on the Mini5+ all seven possible drivers use a common Enable signal.
- The jumper sets the default value in case a M569 command with R parameter isn't seen. The main aim of this is to power up with the drivers disabled.
- The
M569 R#parameter overrides the jumper.
R0 = signal not energised (pulled to +5V) to enable the driver.
R1 = signal energised (pulled to 0V) to enable the driver.
This diagram shows connection to a typical optoisolated stepper motor driver, it is the same as on the 6XD.
For firmware configuration, including mapping drives to axes, configuring enable polarity, and configuring step timing, see the Connecting external stepper and servo drivers wiki page.
¶ Revision History
First version