[Doc] Include safety output pin

Signed-off-by: Pascal Pieper <[email protected]>

config/sample-pwm-tool.cfg

@@ -3,7 +3,7 @@
 # See docs/Using_PWM_Tools.md for a more detailed description.
 
 [output_pin TOOL]
-pin: !ar9       # use your fan's pin number
+pin: !PIN       # use your fan's pin number
 pwm: True
 #hardware_pwm: True
 # Using hardware PWM is optional.
@@ -27,33 +27,40 @@ high_throughput: True
 # needs to be in default speed (off), or else the MCU will
 # do a safety-shutdown.
 
+[output_pin TOOL_ENABLE]
+pin: !OTHER_PIN
+shutdown_value: 0
+
 [gcode_macro M3]
 gcode:
+    SET_PIN PIN=TOOL_ENABLE VALUE=1
     {% set S = params.S|default(0.0)|float %}
     SET_PIN PIN=TOOL VALUE={S / 255.0}
 
 [gcode_macro M4]
 gcode:
+    SET_PIN PIN=TOOL_ENABLE VALUE=1
     {% set S = params.S|default(0.0)|float %}
     SET_PIN PIN=TOOL VALUE={S / 255.0}
 
 [gcode_macro M5]
 gcode:
     SET_PIN PIN=TOOL VALUE=0
+    SET_PIN PIN=TOOL_ENABLE VALUE=0
 
 
 # Optional: LCD Menu Control
 
 [menu __main __control __toolonoff]
 type: input
 enable: {'output_pin TOOL' in printer}
-name: Fan: {'ON ' if menu.input else 'OFF'}
+name: Tool: {'ON ' if menu.input else 'OFF'}
 input: {printer['output_pin TOOL'].value}
 input_min: 0
 input_max: 1
 input_step: 1
 gcode:
-    M3 S{255 if menu.input else 0}
+    SET_PIN PIN=TOOL_ENABLE VALUE={1 if menu.input else 0}
 
 [menu __main __control __toolspeed]
 type: input

docs/Using_PWM_Tools.md

@@ -23,6 +23,8 @@ laser-goggles of the right wavelength if the laser is powered;
 and to disconnect the laser when it is not needed.
 Also, you should consider using a safety timeout,
 so that when your host dies unexpectedly, the tool will stop.
+An additional safety layer would be powering your tool through the hotend-heater pin.
+In the configuration, the additional `[output_pin]` would be activated by `M3/M4` and disabled by `M5`.
 
 For an example configuration, see [config/sample-pwm-tool.cfg](/config/sample-pwm-tool.cfg).