HardwarePWM Class Reference

Basic pulse width modulation support. More...

#include <HardwarePWM.h>

Public Member Functions
	HardwarePWM (const uint8_t *pins, uint8_t no_of_pins)
	Instantiate hardware PWM object. More...
virtual	~HardwarePWM ()
bool	analogWrite (uint8_t pin, uint32_t duty)
	Set PWM duty cycle. More...
bool	setDutyChan (uint8_t chan, uint32_t duty, bool update=true)
	Set PWM duty cycle for a channel. More...
bool	setDuty (uint8_t pin, uint32_t duty, bool update=true)
	Set PWM duty cycle. More...
uint32_t	getDutyChan (uint8_t chan) const
	Get PWM duty cycle. More...
uint32_t	getDuty (uint8_t pin)
	Get PWM duty cycle. More...
void	setPeriod (uint32_t period)
	Set PWM period. More...
uint32_t	getPeriod () const
	Get PWM period. More...
uint8_t	getChannel (uint8_t pin) const
	Get channel number for a pin. More...
uint32_t	getMaxDuty () const
	Get the maximum duty cycle value. More...
void	update ()
	This function is used to actually update the PWM. More...
uint32_t	getFrequency (uint8_t pin) const
	Get PWM Frequency. More...

Detailed Description

Basic pulse width modulation support.

PERIOD: A full PWM cycle has a duration, measured in hardware timer counts DUTY: The 'ON' portion of a PWM cycle measured in hardware timer counts

These values differ between architectures.

DUTY is always <= PERIOD. If DUTY == 0 then output is OFF. If DUTY == PERIOD then output is ON. Intermediate values produce a proportional output, PERCENT = 100 * DUTY / PERIOD.

Producing an analogue voltage from such a PWM output requires a suitable filter with characteristics tuned to the specific PWM frequency in use. A single-pole R/C filter with R*C = PERIOD (in seconds) is often sufficient.

Note: Devices such as servo motors use the digital signal directly.

Note: The Esp8266 has no PWM hardware and uses an interrupt-based approach (software PWM).

Note: Esp32 and Rp2040 hardware offers more capability which requires use of SDK calls or direct hardware access. To avoid resource conflicts avoid using this class in those cases.

Constructor & Destructor Documentation

HardwarePWM()

HardwarePWM::HardwarePWM	(	const uint8_t *	pins,
		uint8_t	no_of_pins
	)

Instantiate hardware PWM object.

Parameters

pins	Pointer to array of pins to control
no_of_pins	Quantity of elements in array of pins

~HardwarePWM()

virtual HardwarePWM::~HardwarePWM ( )

virtual

Member Function Documentation

analogWrite()

bool HardwarePWM::analogWrite ( uint8_t  pin, uint32_t  duty  )

inline

Set PWM duty cycle.

Parameters

pin	GPIO to set
duty	Value of duty cycle to set pin to

Return values

bool	True on success

Note

Default frequency is 1khz but can be varied by various function

getChannel()

uint8_t HardwarePWM::getChannel

(

uint8_t

pin

)

const

Get channel number for a pin.

Parameters

pin	GPIO to interrogate

Return values

uint8_t

Channel of GPIO

getDuty()

uint32_t HardwarePWM::getDuty ( uint8_t  pin )

inline

Get PWM duty cycle.

Parameters

pin	GPIO to get duty cycle for

Return values

uint32_t

Value of PWM duty cycle in timer ticks

getDutyChan()

uint32_t HardwarePWM::getDutyChan

(

uint8_t

chan

)

const

Get PWM duty cycle.

Parameters

chan	Channel to get duty cycle for

Return values

uint32_t

Value of PWM duty cycle in timer ticks

getFrequency()

uint32_t HardwarePWM::getFrequency

(

uint8_t

pin

)

const

Get PWM Frequency.

Parameters

pin	GPIO to get frequency for

Return values

uint32_t

Value of Frequency

getMaxDuty()

uint32_t HardwarePWM::getMaxDuty ( ) const

inline

Get the maximum duty cycle value.

Return values

uint32_t

Maximum permissible duty cycle in timer ticks

Note

Attempt to set duty of a pin above this value will fail

getPeriod()

uint32_t HardwarePWM::getPeriod

(

)

const

Get PWM period.

Return values

uint32_t

Value of PWM period in microseconds

setDuty()

bool HardwarePWM::setDuty ( uint8_t  pin, uint32_t  duty, bool  update = true  )

inline

Set PWM duty cycle.

Parameters

pin	GPIO to set
duty	Value of duty cycle (timer ticks) to set pin to
update	Update PWM output

Return values

bool	True on success

Note

This function is used to set the pwm duty cycle for a given pin. If parameter 'update' is false then you have to call update() later to update duties.

setDutyChan()

bool HardwarePWM::setDutyChan	(	uint8_t	chan,
		uint32_t	duty,
		bool	update = true
	)

Set PWM duty cycle for a channel.

Parameters

chan	Channel to set
duty	Value of duty cycle to set channel to
update	Update PWM output

Return values

bool	True on success

setPeriod()

void HardwarePWM::setPeriod

(

uint32_t

period

)

Set PWM period.

Parameters

period

PWM period in microseconds

Note

All PWM pins share the same period

update()

void HardwarePWM::update

(

)

This function is used to actually update the PWM.

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

• HardwarePWM.h