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Description of Connections
Duet 3 Expansion 3HC provides the following connectors:
2-way barrier strip: two pins for main VIN and GND. VIN power is fused at 10A, individual outputs from the board could add up to >10A (e.g. OUT_0,OUT_1 and OUT_2 are each rated to 6A max) however the total board current should not exceed 10A.
4-pin JST VH DRIVER_0 thru DRIVER_2: Stepper motor connections. (see note on JST VH connectors below)
High current outputs
2-pin JST VH or compatible headers labelled OUT_0 thru OUT_2: these are intended for extruder heaters or fans. Maximum recommended current 6A each. If you connect high-current inductive loads to these outputs, you must use external flyback diodes. (see note on JST VH connectors below)
Medium current/ 4 wire fan outputs
4-pin KK headers with offset spigot OUT_3 thru OUT_5: these are intended for PWM-controllable fans although they can be used for other purposes. Maximum recommended current 2.5A each. The connector fits a standard PC-type 4-pin PWM fan. Alternatively, a 2-pin fan may be connected between the V_OUTLC1 pin (+ve) and the OUT_[n]_NEG pin (-ve). The positive supply to these connectors is the centre pin of the 3-pin jumper block labelled V_OUT3-5. A jumper selects between powering them from the fused VIN supply or the internal 12V regulator (see note on 12V max current below). Alternatively you can connect a 3-terminal buck regulator to the 3-pin jumper block to supply the required voltage to the centre pin.
Medium current/ 2 wire fan outputs
2-pin KK headers labelled OUT_6 thru OUT_8: these are intended for fans. Maximum recommended current 2.5A each. Flyback diodes are built-in to these outputs. The positive supply to these connectors is the centre pin of the 3-pin jumper block labelled V_OUT6-8. A jumper selects between powering them from the fused VIN supply or the internal 12V regulator (see note on 12V max current below).
5-pin KK headers labelled IO_0 thru IO_5: these are for endstop switches, Z probes, filament monitors, servos, and other low-voltage I/O functions. Each connector provides both 3.3V and 5V power. The inputs will tolerate up to 30V. The outputs are 3.3V signals levels with 470R series resistors.
Caution! Check the pinout of these using the wiring diagram linked above before connecting anything to them.
2-pin KK headers labelled TEMP_0 thru TEMP_2: connections for thermistor or PT1000 sensors.
2x5 header: This is for connecting PT100 and thermocouple interface boards (the same boards that the Duet 2 series uses).
2-pin KK headers labelled GND and V+: This is for powering an always-on fan or similar.
6-pin SWD connector: This is for firmware debugging and also provides a backup mechanism to program firmware.
Diagnostic LED: when the expansion board starts up this LED will blank rapidly. If the expansion board is connected to a main board running compatible firmware, the LED on the expansion board will switch to blinking synchronously with the main board LED once time sync has been established across the CAN bus.
Power indication LEDs: There are 4 power indication LEDs:
- Blue: VIN (sensed after the fuse)
- Amber: 12V
- Red: 5V
- Green: 3.3V
JST VH connectors: The 4 wire motor and OUT_0 thru OUT_2 are JST VH series connectors. They require a minimum of 22AWG wire (20AWG or 0.5mm2 recommended). Most NEMA17 size stepper motor wire will will not be thick enough. You will need a suitable crimping tool for the crimp pins, for example Engineer PA21 (use the 2.2mm jaw opening to crimp the bare wire and the 2.5mm on to crimp the insulation). Alternatively you can solder the wire to the crimp pin
Max 12V current :The two banks of Low Current outputs (OUT3-5, OUT6-8) can be separately selected to be powered by either VIN or internal 12V. Total 12V fan current draw must not exceed 800mA.
Prototype wiring is the same as version 1.0 wiring.