pwm_tool: Add support for high-speed PWM pin updates

The output_pin module is only capable of updating an output pin at
most once every 100ms.  Add a new pwm_tool module that is capable of
queuing updates in the micro-controller and thus allowing for much
higher update rates.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/Config_Reference.md

@@ -3127,6 +3127,26 @@ pin:
 #   parameter.
 ```
 
+### [pwm_tool]
+
+Pulse width modulation digital output pins capable of high speed
+updates (one may define any number of sections with an "output_pin"
+prefix). Pins configured here will be setup as output pins and one may
+modify them at run-time using "SET_PIN PIN=my_pin VALUE=.1" type
+extended [g-code commands](G-Codes.md#output_pin).
+
+```
+[pwm_tool my_tool]
+pin:
+#   The pin to configure as an output. This parameter must be provided.
+#value:
+#shutdown_value:
+#cycle_time: 0.100
+#hardware_pwm: False
+#scale:
+#   See the "output_pin" section for the definition of these parameters.
+```
+
 ### [static_digital_output]
 
 Statically configured digital output pins (one may define any number

docs/G-Codes.md

@@ -834,7 +834,8 @@ commands to manage the LED's color settings).
 ### [output_pin]
 
 The following command is available when an
-[output_pin config section](Config_Reference.md#output_pin) is
+[output_pin config section](Config_Reference.md#output_pin) or
+[pwm_tool config section](Config_Reference.md#pwm_tool) is
 enabled.
 
 #### SET_PIN

docs/Status_Reference.md

@@ -318,7 +318,8 @@ is defined):
 ## output_pin
 
 The following information is available in
-[output_pin some_name](Config_Reference.md#output_pin) objects:
+[output_pin some_name](Config_Reference.md#output_pin) and
+[pwm_tool some_name](Config_Reference.md#pwm_tool) objects:
 - `value`: The "value" of the pin, as set by a `SET_PIN` command.
 
 ## palette2

docs/Using_PWM_Tools.md

@@ -1,7 +1,7 @@
 # Using PWM tools
 
 This document describes how to setup a PWM-controlled laser or spindle
-using `output_pin` and some macros.
+using `pwm_tool` and some macros.
 
 ## How does it work?
 
@@ -26,14 +26,6 @@ so that when your host or MCU encounters an error, the tool will stop.
 
 For an example configuration, see [config/sample-pwm-tool.cfg](/config/sample-pwm-tool.cfg).
 
-## 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.