PwmOut Class Reference

A pulse-width modulation digital output. More...

#include <PwmOut.h>

Public Member Functions
	PwmOut (PinName pin)
	Create a PwmOut connected to the specified pin. More...
	PwmOut (const PinMap &pinmap)
	Create a PwmOut connected to the specified pin. More...
void	write (float value)
	Set the output duty-cycle, specified as a percentage (float) More...
float	read ()
	Return the current output duty-cycle setting, measured as a percentage (float) More...
void	period (float seconds)
	Set the PWM period, specified in seconds (float), keeping the duty cycle the same. More...
void	period_ms (int ms)
	Set the PWM period, specified in milliseconds (int), keeping the duty cycle the same. More...
void	period_us (int us)
	Set the PWM period, specified in microseconds (int), keeping the duty cycle the same. More...
int	read_period_us ()
	Read the PWM period. More...
void	pulsewidth (float seconds)
	Set the PWM pulsewidth, specified in seconds (float), keeping the period the same. More...
void	pulsewidth_ms (int ms)
	Set the PWM pulsewidth, specified in milliseconds (int), keeping the period the same. More...
void	pulsewidth_us (int us)
	Set the PWM pulsewidth, specified in microseconds (int), keeping the period the same. More...
int	read_pulsewidth_us ()
	Read the PWM pulsewidth. More...
int	read_pulsewitdth_us ()
	Read the PWM pulsewidth. More...
void	suspend ()
	Suspend PWM operation. More...
void	resume ()
	Resume PWM operation. More...
PwmOut &	operator= (float value)
	A operator shorthand for write() More...
PwmOut &	operator= (PwmOut &rhs)
	A operator shorthand for write() More...
	operator float ()
	An operator shorthand for read() More...

Detailed Description

A pulse-width modulation digital output.

Note

Synchronization level: Interrupt safe

Example

// Gradually change the intensity of the LED.
#include "mbed.h"
 
PwmOut led(LED1);
 
int main() {
    while(1) {
        led = led + 0.01;
        ThisThread::sleep_for(200);
        if(led == 1.0) {
            led = 0;
        }
    }
}

Definition at line 54 of file PwmOut.h.

Constructor & Destructor Documentation

PwmOut() [1/2]

PwmOut

(

PinName

pin

)

Create a PwmOut connected to the specified pin.

Parameters

pin	PwmOut pin to connect to

PwmOut() [2/2]

PwmOut

(

const PinMap &

pinmap

)

Create a PwmOut connected to the specified pin.

Parameters

pinmap

reference to structure which holds static pinmap. This reference is stored in the PwmOut, so the pinmap needs to live as long as this object does.

Member Function Documentation

write()

void write

(

float

value

)

Set the output duty-cycle, specified as a percentage (float)

Parameters

value

A floating-point value representing the output duty-cycle, specified as a percentage. The value should lie between 0.0f (representing on 0%) and 1.0f (representing on 100%). Values outside this range will be saturated to 0.0f or 1.0f.

read()

float read

(

)

Return the current output duty-cycle setting, measured as a percentage (float)

Returns

A floating-point value representing the current duty-cycle being output on the pin, measured as a percentage. The returned value will lie between 0.0f (representing on 0%) and 1.0f (representing on 100%).

Note

This value may not match exactly the value set by a previous write().

period()

void period

(

float

seconds

)

Set the PWM period, specified in seconds (float), keeping the duty cycle the same.

Parameters

seconds

Change the period of a PWM signal in seconds (float) without modifying the duty cycle

Note

The resolution is currently in microseconds; periods smaller than this will be set to zero.

period_ms()

void period_ms

(

int

ms

)

Set the PWM period, specified in milliseconds (int), keeping the duty cycle the same.

Parameters

ms	Change the period of a PWM signal in milliseconds without modifying the duty cycle

period_us()

void period_us

(

int

us

)

Set the PWM period, specified in microseconds (int), keeping the duty cycle the same.

Parameters

us	Change the period of a PWM signal in microseconds without modifying the duty cycle

read_period_us()

int read_period_us

(

)

Read the PWM period.

Returns

The PWM period, specified in microseconds (int)

pulsewidth()

void pulsewidth

(

float

seconds

)

Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.

Parameters

seconds

Change the pulse width of a PWM signal specified in seconds (float)

pulsewidth_ms()

void pulsewidth_ms

(

int

ms

)

Set the PWM pulsewidth, specified in milliseconds (int), keeping the period the same.

Parameters

ms	Change the pulse width of a PWM signal specified in milliseconds

pulsewidth_us()

void pulsewidth_us

(

int

us

)

Set the PWM pulsewidth, specified in microseconds (int), keeping the period the same.

Parameters

us	Change the pulse width of a PWM signal specified in microseconds

read_pulsewidth_us()

int read_pulsewidth_us

(

)

Read the PWM pulsewidth.

Returns

The PWM pulsewidth, specified in microseconds (int)

read_pulsewitdth_us()

int read_pulsewitdth_us

(

)

Read the PWM pulsewidth.

Returns

The PWM pulsewidth, specified in microseconds (int)

suspend()

void suspend

(

)

Suspend PWM operation.

Control the PWM state. This is primarily intended for temporary power-saving; This call can allow pwm to be temporarily disabled to permit power saving without losing device state. The subsequent function call must be PwmOut::resume for PWM to resume; any other calls prior to resuming are undefined behavior.

resume()

void resume

(

)

Resume PWM operation.

Control the PWM state. This is primarily intended to resume PWM operations after a previous PwmOut::suspend call; This call restores the device state prior to suspension.

operator=() [1/2]

PwmOut & operator=

(

float

value

)

A operator shorthand for write()

See also

PwmOut::write()

Definition at line 169 of file PwmOut.h.

operator=() [2/2]

PwmOut & operator=

(

PwmOut &

rhs

)

A operator shorthand for write()

See also

PwmOut::write()

Definition at line 179 of file PwmOut.h.

operator float()

operator float

(

)

An operator shorthand for read()

See also

PwmOut::read()

Definition at line 189 of file PwmOut.h.