Duex5 pwm pin doesnt appear to output anything

RoyMackay

Hi All,
I'm in the process of building a laser engraver from scratch using an atomstack R30 v2 and a duet2 wifi + duex5 board. I've got everything connected on the bench just testing the functions, and I can't get any signal from the duex pwm pin, and thus can't fire the laser. Note for testing I'm just using a multimeter (test location is noted on the schematic) also not that I don't currently have the laser connected (for safety), I'm just trying to confirm the 5v pwm signal is working correctly before I proceed any further. In any case I've attached a wiring mud map of how I've wired the relevant parts, if someone could confirm if the wiring is correct it would be much appreciated

Wiring Mudmap.pdf

Kind Regards
Roydon Mackay

RoyMackay

Sorry should have been explicit, I'm just testing the voltage at the locations shown, multimeter is showing flat zeros

droftarts

@RoyMackay Sorry, I've just seen you previous unanswered thread: https://forum.duet3d.com/topic/36337/initial-setup-of-laser-laser-isn-t-firing-on-g1

Is the config.g the same, except for changing the laser pin from "duex.pwm1" to "duex.pwm1"?
Are you running the same test as in that thread, ie:

G28
M3 S125
G1 X50 F250

If so, the problem is that you need an S parameter in the G1 command, to set the laser power for the duration of the move. The laser will only be on during the move, and will then turn off. See https://docs.duet3d.com/en/User_manual/Machine_configuration/Configuration_laser#controlling-the-laser

So you should use something like:

G1 X50 S128 F250

S128 would set the laser to half power for the duration of this move.

Ian

RoyMackay

@droftarts Hi Ian, Thanks for the reply my config is as follows

; Configuration file for RepRapFirmware on Duet 2 WiFi
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.5.4 on Thu Aug 15 2024 10:24:24 GMT+0800 (Australian Western Standard Time)

; General
G90 ; absolute coordinates
M83 ; relative extruder moves
M550 P"RMACEngraver" ; set hostname

; Network
M552 S0 ; configure WiFi adapter
M586 P0 S1 ; configure HTTP
M586 P1 S1 ; configure FTP
M586 P2 S1 ; configure Telnet

; Smart Drivers
M569 P1 S1 D2 ; driver 1 goes forwards (X axis)
M569 P2 S1 D2 ; driver 2 goes forwards (Y axis)

; Motor Idle Current Reduction
M906 I30 ; set motor current idle factor
M84 S30 ; set motor current idle timeout

; Axes
M584 X1 Y2; set axis mapping
M350 X32 Y32 Z16 I1 ; configure microstepping with interpolation
M906 X2400 Y2400 ; set axis driver currents
M92 X50 Y50 ; configure steps per mm
M208 X0:200 Y0:200 Z0:200 ; set minimum and maximum axis limits
M566 X900 Y900 Z12 ; set maximum instantaneous speed changes (mm/min)
M203 X6000 Y6000 Z180 ; set maximum speeds (mm/min)
M201 X500 Y500 Z20 ; set accelerations (mm/s^2)

; Kinematics
M669 K0 ; configure Cartesian kinematics

; Endstops
M574 X1 S1 P"xstop"  ; configure X axis endstop
M574 Y1 S1 P"ystop"  ; configure Y axis endstop
M574 Z0 ; configure Z axis endstop

; Disable all heaters
M140 H-1 : Disable the bed heater
M307 H1 A-1 C-1 D-1 ; Disable Heater 2 (Hotend)
M307 H1 A-1 C-1 D-1 ; Disable Heater 2 (Chamber)

; Lasers
M563 P0 S"Laser"
M452 C"duex.pwm5" R255 F5000
M42 P"duex.pwm5" S1

T0

I've messed around with a few different things trying to make this work, nothing has given me the pwm signal.
I've just done another test as discussed entering the following
G28
G1 X75 F100 S125
This also didn't give any results. I've also attached the output of a M122 command.
M122.txt
Lastly, I've noticed a reasonable number of unresolved issues in the laser forum around getting this 5v pwm signal to work, is the board actually capable of what I'm trying to do here or is it just limited by the user?

Kind Regards
Roydon Mackay

droftarts

@RoyMackay Can you check what version of RepRapFirmware you are using? Please send M115 and post the response.

; Disable all heaters
M140 H-1 : Disable the bed heater
M307 H1 A-1 C-1 D-1 ; Disable Heater 2 (Hotend)
M307 H1 A-1 C-1 D-1 ; Disable Heater 2 (Chamber)

Assuming you're using RRF 3.x, the above commands are not necessary. No heaters are defined by default, so there's nothing to disable.

; Lasers
M563 P0 S"Laser"
M452 C"duex.pwm5" R255 F5000
M42 P"duex.pwm5" S1

This isn't quite right. The M563 and M452 are fine, but the M42 won't do anything, other than report an error. You can check for errors in your config.g by sending M98 P"config.g". If you want to test the duex.pwm5 (or whichever one you are using), delete the M42 from your config.g, and comment out (with a ; at the beginning of the line) the M452, then reboot.

In the console, enter the following:

M950 P0 C"duex.pwm5"  ; assign GPIO port 0 to heater3 on expansion connector, servo mode
M42 P0 S1

This should turn on the Duex PWM5 output to 5V. Measure between the E6_PWM pin and GND.

Ian