PWM

Pulse-width modulation outputs. More...

Functions
void	pwm_init (const PwmConfig *pwm, uint32_t resolution, uint32_t frequency)
	Initialize a PWM channel.
void	pwm_set_duty_cycle (const PwmConfig *pwm, uint32_t duty_cycle)
	Set the duty cycle.
void	pwm_enable (const PwmConfig *pwm, bool enable)
	Start or stop the output.

Detailed Description

Pulse-width modulation outputs.

A channel is described by a board-defined PwmConfig. The period is resolution counts of a counter running at frequency, so the output frequency is frequency / resolution.

// 256 Hz output with 1024 steps
pwm_init(&BACKLIGHT_PWM.pwm, 1024, 1024 * 256);
pwm_enable(&BACKLIGHT_PWM.pwm, true);
pwm_set_duty_cycle(&BACKLIGHT_PWM.pwm, 512);

Function Documentation

pwm_enable()

void pwm_enable	(	const PwmConfig *	pwm,
		bool	enable
	)

Start or stop the output.

Parameters

pwm	Channel.
enable	true to start, false to stop.

pwm_init()

void pwm_init	(	const PwmConfig *	pwm,
		uint32_t	resolution,
		uint32_t	frequency
	)

Initialize a PWM channel.

Parameters

pwm	Channel.
resolution	Counts per period; duty cycles range from 0 to this value.
frequency	Counter frequency in Hz.

pwm_set_duty_cycle()

void pwm_set_duty_cycle	(	const PwmConfig *	pwm,
		uint32_t	duty_cycle
	)

Set the duty cycle.

The channel must be enabled first.

Parameters

pwm	Channel.
duty_cycle	High time in counts, 0 to the resolution given to pwm_init().