2021-07-22 00:40:40 +02:00
|
|
|
# Using PWM tools
|
|
|
|
|
|
2021-03-26 16:25:09 +01:00
|
|
|
This document describes how to setup a PWM-controlled laser or spindle
|
|
|
|
|
using `output_pin` and some macros.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
## How does it work?
|
|
|
|
|
With re-purposing the printhead's fan pwm output, you can control
|
|
|
|
|
lasers or spindles.
|
|
|
|
|
This is useful if you use switchable print heads, for example
|
|
|
|
|
the E3D toolchanger or a DIY solution.
|
|
|
|
|
Usually, cam-tools such as LaserWeb can be configured to use `M3-M5`
|
|
|
|
|
commands, which stand for _spindle speed CW_ (`M3 S[0-255]`),
|
|
|
|
|
_spindle speed CCW_ (`M4 S[0-255]`) and _spindle stop_ (`M5`).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
**Warning:** When driving a laser, keep all security precautions
|
|
|
|
|
that you can think of! Diode lasers are usually inverted.
|
|
|
|
|
This means, that when the MCU restarts, the laser will be
|
|
|
|
|
_fully on_ for the time it takes the MCU to start up again.
|
|
|
|
|
For good measure, it is recommended to _always_ wear appropriate
|
|
|
|
|
laser-goggles of the right wavelength if the laser is powered;
|
|
|
|
|
and to disconnect the laser when it is not needed.
|
|
|
|
|
Also, you should configure a safety timeout,
|
|
|
|
|
so that when your host or MCU encounters an error, the tool will stop.
|
|
|
|
|
|
2021-09-04 00:10:09 +02:00
|
|
|
For an example configuration, see [config/sample-pwm-tool.cfg](/config/sample-pwm-tool.cfg).
|
2021-03-26 16:25:09 +01:00
|
|
|
|
|
|
|
|
## Current Limitations
|
|
|
|
|
|
|
|
|
|
There is a limitation of how frequent PWM updates may occur.
|
|
|
|
|
While being very precise, a PWM update may only occur every 0.1 seconds,
|
|
|
|
|
rendering it almost useless for raster engraving.
|
|
|
|
|
However, there exists an [experimental branch](https://github.com/Cirromulus/klipper/tree/laser_tool) with its own tradeoffs.
|
|
|
|
|
In long term, it is planned to add this functionality to main-line klipper.
|
|
|
|
|
|
|
|
|
|
## Commands
|
|
|
|
|
|
|
|
|
|
`M3/M4 S<value>` : Set PWM duty-cycle. Values between 0 and 255.
|
|
|
|
|
`M5` : Stop PWM output to shutdown value.
|
|
|
|
|
|
|
|
|
|
## Laserweb Configuration
|
|
|
|
|
|
|
|
|
|
If you use Laserweb, a working configuration would be:
|
|
|
|
|
|
|
|
|
|
GCODE START:
|
|
|
|
|
M5 ; Disable Laser
|
|
|
|
|
G21 ; Set units to mm
|
|
|
|
|
G90 ; Absolute positioning
|
|
|
|
|
G0 Z0 F7000 ; Set Non-Cutting speed
|
|
|
|
|
|
|
|
|
|
GCODE END:
|
|
|
|
|
M5 ; Disable Laser
|
|
|
|
|
G91 ; relative
|
|
|
|
|
G0 Z+20 F4000 ;
|
|
|
|
|
G90 ; absolute
|
|
|
|
|
|
|
|
|
|
GCODE HOMING:
|
|
|
|
|
M5 ; Disable Laser
|
|
|
|
|
G28 ; Home all axis
|
|
|
|
|
|
|
|
|
|
TOOL ON:
|
|
|
|
|
M3 $INTENSITY
|
|
|
|
|
|
|
|
|
|
TOOL OFF:
|
|
|
|
|
M5 ; Disable Laser
|
|
|
|
|
|
|
|
|
|
LASER INTENSITY:
|
|
|
|
|
S
|
