[gnea/grbl-Mega Issue#39] Spindle PWM non-functional

#1 – X3msnake 于 2017-09-25

Are you using a PWM capable pin?

2017-09-23 23:24 GMT+01:00 MaxBareiss :

> I am using this version of grbl-mega with a RAMPS 1.4 board:
>
> $I
> [VER:1.1f.20170802:]
> [OPT:VNML,35,255]
>
> $$
> $0=10
> $1=100
> $2=0
> $3=2
> $4=0
> $5=0
> $6=0
> $10=1
> $11=0.020
> $12=0.002
> $13=0
> $20=0
> $21=0
> $22=1
> $23=0
> $24=500.000
> $25=2000.000
> $26=250
> $27=5.000
> $30=255
> $31=0
> $32=0
> $100=200.000
> $101=200.000
> $102=4535.000
> $110=3000.000
> $111=3000.000
> $112=300.000
> $120=400.000
> $121=400.000
> $122=55.000
> $130=600.000
> $131=600.000
> $132=60.000
>
> I don’t get any spindle PWM. If I turn the spindle on with any value but
> zero (M3 S1) I get full on, and when I turn it off with M5 or M3 S0 it
> turns off, but I don’t get any PWM. I’ve modified this section of
> cpu_map.h:
>
> //Control Digital Pin 6 which is Servo 2 signal pin on Ramps 1.4 board
> #define SPINDLETCCRAREGISTER TCCR4A
> #define SPINDLETCCRBREGISTER TCCR4B
> #define SPINDLEOCRREGISTER OCR4C
> #define SPINDLECOMBBIT COM4C1
>
> // 1/8 Prescaler, 16-bit Fast PWM mode
> #define SPINDLETCCRAINIT_MASK ((1< #define SPINDLETCCRBINIT_MASK ((1< #define SPINDLEOCRAREGISTER OCR4C // 16-bit Fast PWM mode requires top reset value stored here.
> #define SPINDLEOCRATOPVALUE 0x0100 // PWM counter reset value. Should be the same as PWMMAX_VALUE in hex.
>
> // Define spindle output pins.
> #define SPINDLEPWMDDR DDRH
> #define SPINDLEPWMPORT PORTH
> #define SPINDLEPWMBIT 5 // MEGA2560 Digital Pin 8
>
> Because I’m trying to use that PWM pin. It doesn’t work for other pins,
> either. Enable and direction work correctly.
>
> Thanks for any help you can give!
>
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—
Com os melhores cumprimentos,
Vinicius Silva

#2 – MaxBareiss 于 2017-09-25

I figured it out; the issue was that SPINDLEOCRAREGISTER needed to be OCR4A, not OCR4C. I’m going to make a PR soon that makes it clearer that SPINDLEOCRAREGISTER needs to be the ‘A’ register for the timer, regardless of which output pin is used.