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)
virtual void	set_input (float new_value, uint8_t pwm_channel=0) override
Public Member Functions inherited from sensesp::ValueConsumer< float >
void	connect_from (ValueProducer< float > *producer, uint8_t input_channel=0)

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

Protected Attributes
uint8_t	default_channel_

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

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_input() 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
	)

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 15 of file pwm_output.cpp.

Here is the call graph for this function:

Member Function Documentation

assign_channel()

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

static

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 30 of file pwm_output.cpp.

Here is the caller graph for this function:

set_input()

void sensesp::PWMOutput::set_input ( float  new_value, uint8_t  pwm_channel = 0  )

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 21 of file pwm_output.cpp.

Here is the call graph for this function:

set_pwm()

void sensesp::PWMOutput::set_pwm ( int  pwm_channel, float  value  )

static

Sets duty cycle on specified pwm channel

Parameters

pwm_channel	The pwm_channel assigned to the GPIO pin
value	A number between 0.0 and 1.0, where 1.0 is the maximum duty cycle the output pin supports.

Definition at line 54 of file pwm_output.cpp.

Here is the caller graph for this function:

Member Data Documentation

channel_to_pin_

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

staticprotected

Definition at line 73 of file pwm_output.h.

default_channel_

uint8_t sensesp::PWMOutput::default_channel_

protected

Definition at line 74 of file pwm_output.h.

---

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

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