File syn_soft_pwm.h¶

FileList > output > syn_soft_pwm.h

Software PWM on any GPIO pin. More...

#include "../common/syn_defs.h"
#include "../drivers/syn_gpio.h"
#include <stdbool.h>

Classes¶

Type	Name
struct	SYN_SoftPWM Software PWM channel descriptor.

Public Functions¶

Type	Name
void	syn_soft_pwm_init (SYN_SoftPWM * pwm, SYN_GPIO_Pin pin, uint16_t resolution) Initialize a soft PWM channel.
void	syn_soft_pwm_service (SYN_SoftPWM * channels, size_t count) Service an array of PWM channels in one call.
void	syn_soft_pwm_set_duty (SYN_SoftPWM * pwm, uint16_t duty) Set the duty cycle.
void	syn_soft_pwm_set_percent (SYN_SoftPWM * pwm, uint8_t percent) Set duty cycle as a percentage (0–100).
void	syn_soft_pwm_tick (SYN_SoftPWM * pwm) Advance the PWM phase by one tick.

Public Static Functions¶

Type	Name
uint16_t	syn_soft_pwm_get_duty (const SYN_SoftPWM * pwm) Get the current duty cycle value.

Detailed Description¶

When hardware PWM isn't available or you've run out of channels, this module generates PWM by toggling GPIO in a high-frequency tick ISR.

** **

static SYN_SoftPWM pwm;
syn_soft_pwm_init(&pwm, LED_PIN, 100);  // 100 steps resolution
syn_soft_pwm_set_duty(&pwm, 75);         // 75% duty cycle

// Call from a timer ISR at (desired_freq * resolution) Hz:
void TIM_IRQHandler(void) {
    syn_soft_pwm_tick(&pwm);
}

Public Functions Documentation¶

function syn_soft_pwm_init¶

Initialize a soft PWM channel.

void syn_soft_pwm_init (
    SYN_SoftPWM * pwm,
    SYN_GPIO_Pin pin,
    uint16_t resolution
)

Parameters:

pwm PWM instance to initialize.
pin GPIO pin to drive.
resolution Number of steps per PWM period (e.g., 100 or 256). Higher = finer duty control, but requires faster tick.

function syn_soft_pwm_service¶

Service an array of PWM channels in one call.

void syn_soft_pwm_service (
    SYN_SoftPWM * channels,
    size_t count
)

Parameters:

channels Array of PWM instances.
count Number of channels in the array.

function syn_soft_pwm_set_duty¶

Set the duty cycle.

void syn_soft_pwm_set_duty (
    SYN_SoftPWM * pwm,
    uint16_t duty
)

Parameters:

pwm PWM instance.
duty Duty cycle value (0 = off, resolution = 100% on).

function syn_soft_pwm_set_percent¶

Set duty cycle as a percentage (0–100).

void syn_soft_pwm_set_percent (
    SYN_SoftPWM * pwm,
    uint8_t percent
)

Parameters:

pwm PWM instance.
percent Duty cycle percentage (0 to 100).

function syn_soft_pwm_tick¶

Advance the PWM phase by one tick.

void syn_soft_pwm_tick (
    SYN_SoftPWM * pwm
)

Call this from a timer ISR or high-frequency polling loop. The tick rate determines the PWM frequency: PWM_freq = tick_rate / resolution

For example: 10 kHz tick with resolution=100 → 100 Hz PWM.

Parameters:

pwm PWM instance.

Public Static Functions Documentation¶

function syn_soft_pwm_get_duty¶

Get the current duty cycle value.

static inline uint16_t syn_soft_pwm_get_duty (
    const SYN_SoftPWM * pwm
)

Parameters:

pwm PWM instance.

Returns:

Current duty cycle raw value.

The documentation for this class was generated from the following file src/syntropic/output/syn_soft_pwm.h