PWM API
[PWM driver]

With this driver you can control a device with multiple PWM channels. More...

Data Structures
struct	Pwm
	PWM context structure. More...
Enumerations
enum	PwmPolarity { PWM_POL_HIGH_PULSE, PWM_POL_POSITIVE = PWM_POL_HIGH_PULSE, PWM_POL_LOW_PULSE, PWM_POL_NEGATIVE = PWM_POL_LOW_PULSE }
	Enum describing PWM polarities. More...
Functions
void	pwm_setDuty (Pwm *ctx, pwm_duty_t duty)
	Set the duty cycle of the PWM channel linked to ctx.
void	pwm_setFrequency (Pwm *ctx, pwm_freq_t freq)
	Set PWM frequency of channel linked to ctx.
void	pwm_setPolarity (Pwm *ctx, PwmPolarity pol)
	Set PWM polarity of pwm channel linked to ctx.
void	pwm_enable (Pwm *ctx, bool state)
	Enable/Disable the pwm channel linked to ctx.
void	pwm_init (Pwm *ctx, unsigned channel)
	Initialize PWM driver.

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Detailed Description

With this driver you can control a device with multiple PWM channels.

You can enable/disable each channel indipendently and also set frequency and duty cycle.

API usage example:

 Pwm pwm; // declare a context structure
 pwm_init(&pwm, 0); // init pwm channel 0
 pwm_setFrequency(&pwm, 1000); // Set frequency of channel 0 to 1000Hz
 pwm_setDuty(&pwm, 0x7FFF); // Set duty to 50% (0xFFFF/2)
 pwm_enable(&pwm, true); // Activate the output

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Enumeration Type Documentation

enum PwmPolarity

Enum describing PWM polarities.

Enumerator:

PWM_POL_HIGH_PULSE	High pulse: increasing duty increases the part of the signal at high level.
PWM_POL_POSITIVE	Positive pulse: same as High pulse.
PWM_POL_LOW_PULSE	Low pulse: increasing duty increases the part of the signal at low level.
PWM_POL_NEGATIVE	Negative pulse: same as Low pulse.

Definition at line 94 of file pwm.h.

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Function Documentation

void pwm_enable	(	Pwm *	ctx,
		bool	enable
	)

Enable/Disable the pwm channel linked to ctx.

The modification will be applied to the channel immediatly.

Parameters:

	ctx	PWM channel context.
	enable	if true the channel will be enabled, if false will be disabled.

Note:

When a PWM channel is disabled, the output level will be the same as if the duty would be set to 0%. So, if current polarity is positive, a disabled channel will be low, if polarity is negative will be high.

See also:

pwm_setPolarity

Definition at line 220 of file pwm.c.

void pwm_init	(	Pwm *	ctx,
		unsigned	channel
	)

Initialize PWM driver.

Parameters:

	ctx	pointer to a PWM context structure, used for holding PWM driver related information.
	channel	the channel you want to initialize.

Note:

The channel will be initialized disabled and with High polarity.

Definition at line 237 of file pwm.c.

void pwm_setDuty	(	Pwm *	ctx,
		pwm_duty_t	duty
	)

Set the duty cycle of the PWM channel linked to ctx.

The modification will be applied to the channel immediatly. The current frequency of the channel will be maintained.

Parameters:

	ctx	PWM channel context.
	duty	the new duty cycle value.

See also:

pwm_duty_t

Definition at line 168 of file pwm.c.

void pwm_setFrequency	(	Pwm *	ctx,
		pwm_freq_t	freq
	)

Set PWM frequency of channel linked to ctx.

The modification will be applied to the channel immediatly. The duty cycle of the channel will be maintained.

Parameters:

	ctx	PWM channel context.
	freq	the new frequency of the signal, in Hz.

Note:

Depending on the hardware implementation, this function may generate a glitch in the output signal upon frequency changing.

Definition at line 185 of file pwm.c.

void pwm_setPolarity	(	Pwm *	ctx,
		PwmPolarity	pol
	)

Set PWM polarity of pwm channel linked to ctx.

The modification will be applied to the channel immediatly.

Parameters:

	ctx	PWM channel context.
	pol	the new polarity of the signal.

Note:

if a channel is disabled, changing its polarity will change the current steady output level.

See also:

pwm_enable

PwmPolarity

Definition at line 202 of file pwm.c.