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>
This commit is contained in:
Kevin O'Connor 2023-10-13 21:10:11 -04:00
parent 48a05eaa54
commit 29b7550ce5
8 changed files with 201 additions and 17 deletions

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@ -2,9 +2,8 @@
# such as a laser or spindle. # such as a laser or spindle.
# See docs/Using_PWM_Tools.md for a more detailed description. # See docs/Using_PWM_Tools.md for a more detailed description.
[output_pin TOOL] [pwm_tool TOOL]
pin: !ar9 # use your fan's pin number pin: !ar9 # use your fan's pin number
pwm: True
hardware_pwm: True hardware_pwm: True
cycle_time: 0.001 cycle_time: 0.001
shutdown_value: 0 shutdown_value: 0
@ -36,9 +35,9 @@ gcode:
[menu __main __control __toolonoff] [menu __main __control __toolonoff]
type: input type: input
enable: {'output_pin TOOL' in printer} enable: {'pwm_tool TOOL' in printer}
name: Fan: {'ON ' if menu.input else 'OFF'} name: Fan: {'ON ' if menu.input else 'OFF'}
input: {printer['output_pin TOOL'].value} input: {printer['pwm_tool TOOL'].value}
input_min: 0 input_min: 0
input_max: 1 input_max: 1
input_step: 1 input_step: 1
@ -47,9 +46,9 @@ gcode:
[menu __main __control __toolspeed] [menu __main __control __toolspeed]
type: input type: input
enable: {'output_pin TOOL' in printer} enable: {'pwm_tool TOOL' in printer}
name: Tool speed: {'%3d' % (menu.input*100)}% name: Tool speed: {'%3d' % (menu.input*100)}%
input: {printer['output_pin TOOL'].value} input: {printer['pwm_tool TOOL'].value}
input_min: 0 input_min: 0
input_max: 1 input_max: 1
input_step: 0.01 input_step: 0.01

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@ -3127,6 +3127,26 @@ pin:
# parameter. # 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] ### [static_digital_output]
Statically configured digital output pins (one may define any number Statically configured digital output pins (one may define any number

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

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@ -318,7 +318,8 @@ is defined):
## output_pin ## output_pin
The following information is available in 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. - `value`: The "value" of the pin, as set by a `SET_PIN` command.
## palette2 ## palette2

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@ -1,7 +1,7 @@
# Using PWM tools # Using PWM tools
This document describes how to setup a PWM-controlled laser or spindle 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? ## 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). 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 ## Commands
`M3/M4 S<value>` : Set PWM duty-cycle. Values between 0 and 255. `M3/M4 S<value>` : Set PWM duty-cycle. Values between 0 and 255.

157
klippy/extras/pwm_tool.py Normal file
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@ -0,0 +1,157 @@
# Queued PWM gpio output
#
# Copyright (C) 2017-2023 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import chelper
PIN_MIN_TIME = 0.100
MAX_SCHEDULE_TIME = 5.0
class error(Exception):
pass
class MCU_queued_pwm:
def __init__(self, pin_params):
self._mcu = pin_params['chip']
self._hardware_pwm = False
self._cycle_time = 0.100
self._max_duration = 2.
self._oid = self._mcu.create_oid()
ffi_main, ffi_lib = chelper.get_ffi()
self._stepqueue = ffi_main.gc(ffi_lib.stepcompress_alloc(self._oid),
ffi_lib.stepcompress_free)
self._mcu.register_stepqueue(self._stepqueue)
self._stepcompress_queue_mq_msg = ffi_lib.stepcompress_queue_mq_msg
self._mcu.register_config_callback(self._build_config)
self._pin = pin_params['pin']
self._invert = pin_params['invert']
self._start_value = self._shutdown_value = float(self._invert)
self._last_clock = self._cycle_ticks = 0
self._pwm_max = 0.
self._set_cmd_tag = None
def get_mcu(self):
return self._mcu
def setup_max_duration(self, max_duration):
self._max_duration = max_duration
def setup_cycle_time(self, cycle_time, hardware_pwm=False):
self._cycle_time = cycle_time
self._hardware_pwm = hardware_pwm
def setup_start_value(self, start_value, shutdown_value):
if self._invert:
start_value = 1. - start_value
shutdown_value = 1. - shutdown_value
self._start_value = max(0., min(1., start_value))
self._shutdown_value = max(0., min(1., shutdown_value))
def _build_config(self):
if self._max_duration and self._start_value != self._shutdown_value:
raise pins.error("Pin with max duration must have start"
" value equal to shutdown value")
cmd_queue = self._mcu.alloc_command_queue()
curtime = self._mcu.get_printer().get_reactor().monotonic()
printtime = self._mcu.estimated_print_time(curtime)
self._last_clock = self._mcu.print_time_to_clock(printtime + 0.200)
cycle_ticks = self._mcu.seconds_to_clock(self._cycle_time)
mdur_ticks = self._mcu.seconds_to_clock(self._max_duration)
if mdur_ticks >= 1<<31:
raise pins.error("PWM pin max duration too large")
if self._hardware_pwm:
self._pwm_max = self._mcu.get_constant_float("PWM_MAX")
self._mcu.add_config_cmd(
"config_pwm_out oid=%d pin=%s cycle_ticks=%d value=%d"
" default_value=%d max_duration=%d"
% (self._oid, self._pin, cycle_ticks,
self._start_value * self._pwm_max,
self._shutdown_value * self._pwm_max, mdur_ticks))
svalue = int(self._start_value * self._pwm_max + 0.5)
self._mcu.add_config_cmd("queue_pwm_out oid=%d clock=%d value=%d"
% (self._oid, self._last_clock, svalue),
on_restart=True)
self._set_cmd_tag = self._mcu.lookup_command(
"queue_pwm_out oid=%c clock=%u value=%hu",
cq=cmd_queue).get_command_tag()
return
# Software PWM
if self._shutdown_value not in [0., 1.]:
raise pins.error("shutdown value must be 0.0 or 1.0 on soft pwm")
if cycle_ticks >= 1<<31:
raise pins.error("PWM pin cycle time too large")
self._mcu.add_config_cmd(
"config_digital_out oid=%d pin=%s value=%d"
" default_value=%d max_duration=%d"
% (self._oid, self._pin, self._start_value >= 1.0,
self._shutdown_value >= 0.5, mdur_ticks))
self._mcu.add_config_cmd(
"set_digital_out_pwm_cycle oid=%d cycle_ticks=%d"
% (self._oid, cycle_ticks))
self._cycle_ticks = cycle_ticks
svalue = int(self._start_value * cycle_ticks + 0.5)
self._mcu.add_config_cmd(
"queue_digital_out oid=%d clock=%d on_ticks=%d"
% (self._oid, self._last_clock, svalue), is_init=True)
self._set_cmd_tag = self._mcu.lookup_command(
"queue_digital_out oid=%c clock=%u on_ticks=%u",
cq=cmd_queue).get_command_tag()
def set_pwm(self, print_time, value):
clock = self._mcu.print_time_to_clock(print_time)
minclock = self._last_clock
self._last_clock = clock
if self._invert:
value = 1. - value
max_count = self._cycle_ticks
if self._hardware_pwm:
max_count = self._pwm_max
v = int(max(0., min(1., value)) * max_count + 0.5)
data = (self._set_cmd_tag, self._oid, clock & 0xffffffff, v)
ret = self._stepcompress_queue_mq_msg(self._stepqueue, clock,
data, len(data))
if ret:
raise error("Internal error in stepcompress")
class PrinterOutputPin:
def __init__(self, config):
self.printer = config.get_printer()
ppins = self.printer.lookup_object('pins')
# Determine pin type
pin_params = ppins.lookup_pin(config.get('pin'), can_invert=True)
self.mcu_pin = MCU_queued_pwm(pin_params)
cycle_time = config.getfloat('cycle_time', 0.100, above=0.,
maxval=MAX_SCHEDULE_TIME)
hardware_pwm = config.getboolean('hardware_pwm', False)
self.mcu_pin.setup_cycle_time(cycle_time, hardware_pwm)
self.scale = config.getfloat('scale', 1., above=0.)
self.last_print_time = 0.
self.mcu_pin.setup_max_duration(0.)
# Determine start and shutdown values
self.last_value = config.getfloat(
'value', 0., minval=0., maxval=self.scale) / self.scale
self.shutdown_value = config.getfloat(
'shutdown_value', 0., minval=0., maxval=self.scale) / self.scale
self.mcu_pin.setup_start_value(self.last_value, self.shutdown_value)
# Register commands
pin_name = config.get_name().split()[1]
gcode = self.printer.lookup_object('gcode')
gcode.register_mux_command("SET_PIN", "PIN", pin_name,
self.cmd_SET_PIN,
desc=self.cmd_SET_PIN_help)
def get_status(self, eventtime):
return {'value': self.last_value}
def _set_pin(self, print_time, value):
if value == self.last_value:
return
print_time = max(print_time, self.last_print_time)
self.mcu_pin.set_pwm(print_time, value)
self.last_value = value
self.last_print_time = print_time
cmd_SET_PIN_help = "Set the value of an output pin"
def cmd_SET_PIN(self, gcmd):
# Read requested value
value = gcmd.get_float('VALUE', minval=0., maxval=self.scale)
value /= self.scale
# Obtain print_time and apply requested settings
toolhead = self.printer.lookup_object('toolhead')
toolhead.register_lookahead_callback(
lambda print_time: self._set_pin(print_time, value))
def load_config_prefix(config):
return PrinterOutputPin(config)

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@ -13,6 +13,12 @@ value: 0
shutdown_value: 0 shutdown_value: 0
cycle_time: 0.01 cycle_time: 0.01
[pwm_tool test_pwm_tool]
pin: PH4
value: 0
shutdown_value: 0
cycle_time: 0.01
[mcu] [mcu]
serial: /dev/ttyACM0 serial: /dev/ttyACM0

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@ -28,3 +28,11 @@ SET_PIN PIN=soft_pwm_pin VALUE=0.5 CYCLE_TIME=0.5
SET_PIN PIN=soft_pwm_pin VALUE=0.5 CYCLE_TIME=0.5 SET_PIN PIN=soft_pwm_pin VALUE=0.5 CYCLE_TIME=0.5
SET_PIN PIN=soft_pwm_pin VALUE=0.75 CYCLE_TIME=0.5 SET_PIN PIN=soft_pwm_pin VALUE=0.75 CYCLE_TIME=0.5
SET_PIN PIN=soft_pwm_pin VALUE=0.75 CYCLE_TIME=0.75 SET_PIN PIN=soft_pwm_pin VALUE=0.75 CYCLE_TIME=0.75
# PWM tool
# Basic test
SET_PIN PIN=test_pwm_tool VALUE=0
SET_PIN PIN=test_pwm_tool VALUE=0.5
SET_PIN PIN=test_pwm_tool VALUE=0.5
SET_PIN PIN=test_pwm_tool VALUE=0.25
SET_PIN PIN=test_pwm_tool VALUE=1