sensesp::PWMOutput Class Reference

Provides a cross platform mechanism for generating Pulse Width Modulation signals over one or more GPIO pins on the MCU. More...

#include <sensesp/system/pwm_output.h>

Inheritance diagram for sensesp::PWMOutput:

Public Member Functions
	PWMOutput (int pin=-1, int pwm_channel=-1, int channel_frequency=5000, int channel_resolution=13)
virtual void	set (const float &new_value) override
Public Member Functions inherited from sensesp::ValueConsumer< float >
virtual void	set_input (const float &new_value)
void	connect_from (ValueProducer< float > *producer)

Protected Member Functions
int	assign_channel (int pin, int pwm_channel=-1)
void	set_pwm (float value)

Protected Attributes
int	channel_frequency_
int	channel_resolution_
int	pwmrange_
uint8_t	pwm_channel_ {}

Static Protected Attributes
static std::map< uint8_t, int8_t >	channel_to_pin_

Additional Inherited Members
Public Types inherited from sensesp::ValueConsumer< float >
using	input_type

Detailed Description

Provides a cross platform mechanism for generating Pulse Width Modulation signals over one or more GPIO pins on the MCU.

This class works by defining a "PWM channel". GPIO pins are assigned to a channel, and then the channel is used when setting the pwm value. The pwm value is a float number between 0.0 and 1.0, interpreted as a percentage of the maximum duty cycle possible.

Channels can be auto-assigned to a pin or they can be declared explicitly in your code. The PWM value is set either by calling set_pwm(), or by using an instance of PWMOutput and calling the set() method as defined in ValueConsumer<>.

On an esp32, the "channel" corresponds to one of the timer channels available on the onboard chip. Explicit declaration of a channel may or may not be necessary depending on other libraries that you may be using. Unless you have a need to use an explicit channel (e.g. if some other software is already using a particular esp32 timer channel), the channel auto-assign feature is the easiest to use. In either event, using this channel number allows the same code to work on either platform.

Definition at line 32 of file pwm_output.h.

Constructor & Destructor Documentation

PWMOutput()

sensesp::PWMOutput::PWMOutput	(	int	pin = -1,
		int	pwm_channel = -1,
		int	channel_frequency = 5000,
		int	channel_resolution = 13 )

Creates an instance of a PWMOutput ValueConsumer.

Parameters

pin	The GPIO pin used to output the pwm signal. Pass -1 if this instance does not manage a specific pin. Using -1 is only valid if channel assignments have been explicitly made by calling PWMOutput::assign_channel()
pwm_channel	The pwm channel the GPIO pin is to be assigned to. Pass -1 if you would like the system to auto-select the next unassigned pin.

Definition at line 14 of file pwm_output.cpp.

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Member Function Documentation

assign_channel()

int sensesp::PWMOutput::assign_channel ( int pin, int pwm_channel = -1 )

protected

Assigns the specified GPIO pin to the specified pwm channel.

Parameters

pin	the GPIO pin used for the pwm output
pwm_channel	The pwm_channel to the GPIO pin is assigned to. Passing -1 specifies you would like to use the next unassigned channel available.

Returns

The actual pwm channel assigned to the GPIO pin to the pin

Definition at line 28 of file pwm_output.cpp.

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set()

void sensesp::PWMOutput::set ( const float & new_value )

overridevirtual

Sets the duty cycle of the specified pwm_channel to new_value. If pwm_channel is zero, the channel assigned when the PWMOutput instance was instantiated will be used.

Reimplemented from sensesp::ValueConsumer< float >.

Definition at line 26 of file pwm_output.cpp.

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set_pwm()

void sensesp::PWMOutput::set_pwm ( float value )

protected

Sets duty cycle on specified pwm channel

Parameters

value

A number between 0.0 and 1.0, where 1.0 is the maximum duty cycle the output pin supports.

Definition at line 50 of file pwm_output.cpp.

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Member Data Documentation

channel_frequency_

int sensesp::PWMOutput::channel_frequency_

protected

Definition at line 55 of file pwm_output.h.

channel_resolution_

int sensesp::PWMOutput::channel_resolution_

protected

Definition at line 56 of file pwm_output.h.

channel_to_pin_

std::map< uint8_t, int8_t > sensesp::PWMOutput::channel_to_pin_

staticprotected

Definition at line 59 of file pwm_output.h.

pwm_channel_

uint8_t sensesp::PWMOutput::pwm_channel_ {}

protected

Definition at line 60 of file pwm_output.h.

pwmrange_

int sensesp::PWMOutput::pwmrange_

protected

Definition at line 57 of file pwm_output.h.

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The documentation for this class was generated from the following files:

• src/sensesp/system/pwm_output.h
• src/sensesp/system/pwm_output.cpp