BTT Rodent Spindle PWM

[agentnoise]

I have grblHAL installed on a BTT rodent and the spindle pwm port is sending full voltage on every value over 24. So M3 S24 is the same as M3 S12000. Full send no matter what

I built the firmware using the web builder. Is this a known issue? Is there a way to correct it?

$I
[VER:1.1f.20260303:]
$spindles
0 - PWM

[terjeio]

When I test with a dev board the PWM output is working fine.
What are your settings? $30 - $36 are the most relevant.

[agentnoise]

$30=12000.000
$36=100.0

I'm using the Rodent 1.1 board.

All of the settings if you need them
$0=5.0
$1=25
$2=0
$3=6
$4=7
$5=7
$6=1
$8=0
$9=1
$10=511
$11=0.010
$12=0.002
$13=0
$14=0
$15=0
$16=0
$17=0
$18=0
$19=0
$20=0
$21=0
$22=35
$23=0
$24=50.0
$25=900.0
$26=250
$27=3.000
$28=0.100
$29=0.0
$30=12000.000
$31=0.000
$32=0
$33=1000.0
$34=0.0
$35=0.0
$36=100.0
$37=0
$39=1
$40=0
$41=0
$42=2
$43=1
$44=4
$45=3
$46=0
$56=5.0
$57=100.0
$58=-5.0
$59=500.0
$60=0
$61=0
$62=0
$63=3
$64=0
$65=0
$70=6
$73=1
$74=Garage_2.4ghz
$75=********
$76=grblHAL_AP
$77=********
$78=01
$79=1
$100=400.00000
$101=400.00000
$102=400.00000
$110=4000.000
$111=4000.000
$112=4000.000
$120=10.000
$121=10.000
$122=10.000
$130=200.000
$131=400.000
$132=200.000
$140=1500
$141=1500
$142=1500
$150=8
$151=8
$152=8
$200=22.0
$201=22.0
$202=22.0
$210=50
$211=50
$212=50
$220=22.0
$221=22.0
$222=22.0
$310=grblHAL_AP
$312=192.168.5.1
$313=192.168.5.1
$314=255.255.255.0
$320=grblHAL
$322=192.168.5.1
$323=192.168.5.1
$324=255.255.255.0
$326=80
$327=81
$337=
$338=7
$339=0
$341=0
$342=30.0
$343=25.0
$344=200.0
$345=200.0
$346=1
$384=0
$392=4.0
$393=1.0
$394=0.0
$396=30
$397=0
$398=100
$481=0
$484=1
$485=0
$486=0
$534=0
$539=0.0
$650=0
$673=0.0
$675=0
$676=15
$680=0
$700=0

[terjeio]

Settings looks ok, only thing that seems strange is why reducing the PWM frequency to 1000Hz? IMO that would only increase ripple at the output of U21A.
To debug I wonder if it is possible to measure the voltage at either end of R225 that feeds the PWM -> 0-10V converter op-amp. Are those ok?

[agentnoise]

I'll try setting it back to 5k, that was just a test. Are you saying, test the voltage of the GPIO pin before it hits the op-amp? I can try, not sure the pin is exposed in a way I can access.

[terjeio]

If you can find R225 the you can measure at each end of that:

[agentnoise]

I can't easily identify R225 but I can see the LM358. It looks like a hardware problem with the feedback. Pin 3 on the LM358 changes voltage as expected. Pin 1 is a steady 10v no matter what and pin 2 is 0v no matter what. So R226 is likely bad (according to the schematic). Maybe I can resolder or get a replacement