Pwm Class Reference

Detailed Description

This file defines the PWM interface for libmraa

    mraa::Pwm* pwm;

    pwm = new mraa::Pwm(3);
    if (pwm == NULL) {
        return MRAA_ERROR_UNSPECIFIED;
    }
    fprintf(stdout, "Cycling PWM on IO3 (pwm3) \n");
    pwm->enable(true);

    float value = 0.0f;
    while (running == 0) {
        value = value + 0.01f;
        pwm->write(value);
        usleep(50000);
        if (value >= 1.0f) {
            value = 0.0f;
        }
    }
    delete pwm;

Public Member Functions
	Pwm (int pin, bool owner=true, int chipid=-1)
	Pwm (void *pwm_context)
	~Pwm ()
Result	write (float percentage)
float	read ()
Result	period (float period)
Result	period_ms (int ms)
Result	period_us (int us)
Result	pulsewidth (float seconds)
Result	pulsewidth_ms (int ms)
Result	pulsewidth_us (int us)
Result	enable (bool enable)
int	max_period ()
int	min_period ()

Constructor & Destructor Documentation

Pwm ( int  pin, bool  owner = true, int  chipid = -1  )

inline

instanciates a PWM object on a pin

Parameters

pin	the pin number used on your board
owner	if you are the owner of the pin the destructor will unexport the pin from sysfs, default behaviour is you are the owner if the pinmapper exported it
chipid	the pwmchip to use, use only in raw mode

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Pwm ( void *  pwm_context )

inline

Pwm constructor, takes a pointer to the PWM context and initialises the class

Parameters

void	* to a PWM context

~Pwm ( )

inline

Pwm destructor

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Member Function Documentation

Result write ( float  percentage )

inline

Set the output duty-cycle percentage, as a float

Parameters

percentage

A floating-point value representing percentage of output. The value should lie between 0.0f (representing 0%) and 1.0f Values above or below this range will be set at either 0.0f or 1.0f

Returns

Result of operation

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float read ( )

inline

Read the output duty-cycle percentage, as a float

Returns

A floating-point value representing percentage of output. The value should lie between 0.0f (representing 0%) and 1.0f Values above or below this range will be set at either 0.0f or 1.0f

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Result period ( float  period )

inline

Set the PWM period as seconds represented in a float

Parameters

period

Period represented as a float in seconds

Returns

Result of operation

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Result period_ms ( int  ms )

inline

Set period, milliseconds

Parameters

ms	milliseconds for period

Returns

Result of operation

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Result period_us ( int  us )

inline

Set period, microseconds

Parameters

us	microseconds as period

Returns

Result of operation

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Result pulsewidth ( float  seconds )

inline

Set pulsewidth, as represented by seconds in a float

Parameters

seconds

The duration of a pulse

Returns

Result of operation

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Result pulsewidth_ms ( int  ms )

inline

Set pulsewidth, milliseconds

Parameters

ms	milliseconds for pulsewidth

Returns

Result of operation

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Result pulsewidth_us ( int  us )

inline

The pulsewidth, microseconds

Parameters

us	microseconds for pulsewidth

Returns

Result of operation

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Result enable ( bool  enable )

inline

Set the enable status of the PWM pin. None zero will assume on with output being driven and 0 will disable the output

Parameters

enable

enable status of pin

Returns

Result of operation

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int max_period ( )

inline

Get the maximum PWM period in us

Returns

max PWM period in us

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int min_period ( )

inline

Get the minimum PWM period in us

Returns

min PWM period in us

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

• api/mraa/pwm.hpp