Hi everyone! Was looking to set up my acro 1510 when it arrives soon and going to use the S9 laser from sculpfun. But I need to know the PWM output spectrum of the black box (have looked through the docs and couldn't find anything). I know in grbl the command to set the PWM is the S command, but the laser itself has full power output PWM = 10KHz. So was hoping that the blackbox can do this with the S command without having to make a frequency multiplier. Does anyone know if the black box can output up to 10KHz? Thanks for any help in advance
See Grbl's compile time directives: grbl/cpu_map.h at master · gnea/grbl Can you provide a link or details? Seems to be just a standard diode laser, they like 1khz PWM too Remember, PWM = pulse width (not frequency) - the duty cycle sets the power. Not the frequency. Understanding pulse width modulation - Knowledge Kitchen Within different S-values the frequency is a constant - the length of the 'on' versus 'off' periods within each cycle just differ.
Hi Peter! Thanks for your reply, sure thing, the laser is: SCULPFUN S9 Laser Module-Shenzhen Sculpfun Technology Co., Ltd. Ah, just found on their site, it says 0-1KHz, but the info leaflet they sent said 10KHz, so looks like it is 1KHz after all! Also, I found this definition in the code block you sent: // Variable spindle configuration below. Do not change unless you know what you are doing. // NOTE: Only used when variable spindle is enabled. #define SPINDLE_PWM_MAX_VALUE 255 // Don't change. 328p fast PWM mode fixes top value as 255 I'm hoping this doesn't mean the max PWM is 255Hz! Is that a value from 0 to 255 in the command value which then gives 0 - 1KHz output? Or is that 0 - 255 Hz output?
No, See Understanding pulse width modulation - Knowledge Kitchen PWM freq = 1khz+- there are 255 "steps" of pwm duty cycles (think of it as 255 shades of gray in laser engraving) - PWM = pulse width modulation, it's not FM (frequency modulation - familiar as standard FM radios) In PWM - Frequency is constant, duty cycle changes. Nothing special about that laser - standard 5.5w diode laser like the ones we recommend (except our recommended vendors has a lot less untruths than some of the nonsense I read on that link... 90w equivalent power - yeah sure lol)
Thanks Peter! Ah so it is duty cycle and not frequency, I though it was frequency! Thanks for the heads up. So for the S command in G code, is the specification of output in the range from S0 to S255?
Correct Or S0 to S-whatever. There are 255 steps, but for easier reading gcode, Grbl 1.1 uses S0-S1000 by default (still 255 steps, just S-value/1000*255 internally) - you can even set your own value in $30. For example the spindle guys sets $30=24000 so S24000 means 24k-RPM and it makes more sense than trying to remember S255 is 24k-RPM
Also see Grbl v1.1 Laser Mode · gnea/grbl Wiki and docs:blackbox:start [OpenBuilds Documentation] (Sections 3.3.2, 3.3.3) and also docs:software:overview [OpenBuilds Documentation] - and probably docs:software:lightburn [OpenBuilds Documentation]
