@dc42
I have the Duet 3 6hc in my open build machine, I followed your wiring scheme and used io5.
Here is my config.
firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.2.3 on Mon Mar 08 2021 08:53:31 GMT-0600 (Central Standard Time)
; General preferences
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"Colossus Openbuild" ; set printer name
; Network
M552 P0.0.0.0 S1 ; enable network and acquire dynamic address via DHCP
M586 P0 S1 ; enable HTTP
M586 P1 S0 ; disable FTP
M586 P2 S0 ; disable Telnet
; Drives
M569 P0.3 S1 ; physical drive 0.3 goes forwards
M569 P0.2 S1 ; physical drive 0.2 goes forwards
M569 P0.0 S1 ; physical drive 0.0 goes forwards
M569 P0.4 S1 ; physical drive 0.4 goes forwards
M584 X0.3 Y0.2 Z0.0:0.1 E0.4 ; set drive mapping
M671 X-122.25:689.20 Y0:0 S3.0 ; leadscrews at left (connected to Z0) and right (connected to Z1) of X axis
M350 X32 Y32 Z32 E16 I1 ; configure microstepping with interpolation
M92 X106.5 Y257 Z795.00 E339.00 ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2)
M906 X900 Y3000 Z3000 E800 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout
; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X609 Y609 Z762 S0 ; set axis maxima
; Endstops
M574 X1 S1 P"!^io1.in" ; configure active-high endstop for low end on X via pin !^io1.in
M574 Y1 S1 P"!^io2.in" ; configure active-high endstop for low end on Y via pin !^io2.in
M574 Z1 S2 ; configure Z-probe endstop for low end on Z
M591 D0 P7 C"io5.in" L7 R55:150 E22 S1 ;Bigtree smart filament moniter v2 set to moniter between 55%-150% of 7 counts over a distance of 22mm
M591 D0 ; display filament sensor parameters for extruder drive 4
; Z-Probe
M950 S0 C"io7.out" ; create servo pin 0 for BLTouch
M558 P9 C"^io7.in" H5 F120 T6000 ; set Z probe type to bltouch and the dive height + speeds
G31 P100 X60 Y0 Z1.272 ; set Z probe trigger value, offset and trigger height
M557 X100:500 Y100:500 S100 ; define mesh grid
; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out1" T0 ; create bed heater output on out1 and map it to sensor 0
M307 H0 B1 S10.00 ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S110 ; set temperature limit for heater 0 to 120C
M308 S1 P"temp1" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out2" T1 ; create nozzle heater output on out2 and map it to sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S280 ; set temperature limit for heater 1 to 280C
; Fans
M950 F0 C"out8" Q500 ; create fan 0 on pin out8 and set its frequency
M106 P0 C"Tool Fan" S0 H-1 ; set fan 0 name and value. Thermostatic control is turned off
M950 F1 C"out6" Q500 ; create fan 1 on pin out6 and set its frequency
M950 F2 C"out7" Q500 ; create fan 2 on pin out7 and set its frequency
M106 P1 C"Extruder" S1 H1 T45 ; set fan 1 name and value. Thermostatic control is turned on
; Tools
M563 P0 S"Hemera" D0 H1 F0 ; define tool 0
G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C
; Custom settings are not defined
; Miscellaneous
M575 P1 S1 B57600 ; enable support for PanelDue
all I needed to do was wire 3.3vdc to pin 1, io5.in to pin 3 and ground to pin 4 and it works great