RPI_PWM Class Reference

Class to create a Pulse Width Modulated (PWM) signal on the Raspberry PI 4 and 5. More...

#include <uPWM.h>

Public Member Functions
int	start (int channel, int frequency, float duty_cycle=0, int chip=2)
	Starts the PWM.
void	stop ()
	Stops the PWM.
	~RPI_PWM ()
	Destroy the RPI_PWM object.
int	setDutyCycle (float v) const
	Sets the duty cycle in percent 0 - 100.

Private Member Functions
void	setPeriod (int ns) const
int	setDutyCycleNS (int ns) const
void	enable () const
void	disable () const
int	writeSYS (std::string filename, int value) const

Private Attributes
int	per = 0
std::string	chippath
std::string	pwmpath

Detailed Description

Class to create a Pulse Width Modulated (PWM) signal on the Raspberry PI 4 and 5.

Based on https://github.com/berndporr/rpi_pwm/blob/main/rpi_pwm.h and slightly modified.

For servo control it is important to use a hardware generated PWM, since software PWM, like it is created by the lgpio library, is subject to timing jitter which can cause the servo to figet which might lead to overheating and wear.

Constructor & Destructor Documentation

~RPI_PWM()

RPI_PWM::~RPI_PWM ( )

inline

Destroy the RPI_PWM object.

Invokes disable()

Member Function Documentation

disable()

void RPI_PWM::disable ( ) const

inlineprivate

enable()

void RPI_PWM::enable ( ) const

inlineprivate

setDutyCycle()

int RPI_PWM::setDutyCycle ( float  v ) const

inline

Sets the duty cycle in percent 0 - 100.

Parameters

v	The duty cycle in percent.

Returns

>0 on success and -1 after an error.

setDutyCycleNS()

int RPI_PWM::setDutyCycleNS ( int  ns ) const

inlineprivate

setPeriod()

void RPI_PWM::setPeriod ( int  ns ) const

inlineprivate

start()

int RPI_PWM::start ( int  channel, int  frequency, float  duty_cycle = 0, int  chip = 2  )

inline

Starts the PWM.

Parameters

channel	The GPIO channel
frequency	The PWM frequency
duty_cycle	The initial duty cycle of the PWM (default 0)
chip	The chip number

Returns

>0 on success and -1 if an error has happened.

stop()

void RPI_PWM::stop ( )

inline

Stops the PWM.

writeSYS()

int RPI_PWM::writeSYS ( std::string  filename, int  value  ) const

inlineprivate

Member Data Documentation

chippath

std::string RPI_PWM::chippath

private

per

int RPI_PWM::per = 0

private

pwmpath

std::string RPI_PWM::pwmpath

private

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

• lib/ros2_ws/src/dalsa_bioscara_grippers/bioscara_gripper_hardware_driver/include/bioscara_gripper_hardware_driver/uPWM.h