pwm.c File Reference

PWM driver implementation for STM32F4 series (Cortex-M4) More...

#include "core/cortex-m4/pwm.h"
#include "core/cortex-m4/clock.h"
#include "core/cortex-m4/timer.h"
#include <stdint.h>

Include dependency graph for pwm.c:

Functions
void	hal_pwm_init (PWM_Handle *pwm, uint32_t frequency, float dutyCycle)
	Initialize PWM with specified frequency and duty cycle.
void	hal_pwm_start (PWM_Handle *pwm)
	Start PWM output.
void	hal_pwm_stop (PWM_Handle *pwm)
	Stop PWM output.
void	hal_pwm_set_duty_cycle (PWM_Handle *pwm, float dutyCycle)
	Set PWM duty cycle.
void	hal_pwm_set_frequency (PWM_Handle *pwm, uint32_t frequency)
	Set PWM frequency (not implemented)

Detailed Description

PWM driver implementation for STM32F4 series (Cortex-M4)

This file provides Pulse Width Modulation (PWM) functionality for STM32F4 microcontrollers. It supports:

• PWM generation on all timer channels
• Configurable frequency and duty cycle
• Automatic timer clock selection (APB1/APB2)
• Runtime duty cycle adjustment

The implementation uses the STM32 timer peripherals to generate precise PWM signals with minimal CPU overhead.

Copyright

© NAVROBOTEC PVT. LTD.

Function Documentation

hal_pwm_init()

void hal_pwm_init	(	PWM_Handle *	pwm,
		uint32_t	frequency,
		float	dutyCycle )

Initialize PWM with specified frequency and duty cycle.

Initialize a PWM handle with the specified frequency and duty cycle.

Parameters

[in,out]	pwm	Pointer to PWM handle structure
[in]	frequency	Desired PWM frequency in Hz
[in]	dutyCycle	Initial duty cycle (0.0 to 1.0)

Configures the timer peripheral to generate PWM signals by:

1. Selecting the appropriate bus clock (APB1/APB2)
2. Calculating prescaler and auto-reload values
3. Setting the initial compare value for duty cycle
4. Initializing the timer peripheral

Note

For advanced timers (TIM1, TIM9-TIM11), APB2 clock is used automatically

hal_pwm_set_duty_cycle()

void hal_pwm_set_duty_cycle	(	PWM_Handle *	pwm,
		float	dutyCycle )

Set PWM duty cycle.

Set the PWM duty cycle.

Parameters

[in,out]	pwm	Pointer to PWM handle structure
[in]	dutyCycle	New duty cycle (0.0 to 1.0)

Updates the capture/compare register to change the PWM duty cycle while maintaining the current frequency. The change takes effect immediately on the output.

Note

Duty cycle is clamped to valid range (0.0-1.0)

hal_pwm_set_frequency()

void hal_pwm_set_frequency	(	PWM_Handle *	pwm,
		uint32_t	frequency )

Set PWM frequency (not implemented)

Set the PWM frequency.

Parameters

[in,out]	pwm	Pointer to PWM handle structure
[in]	frequency	Desired PWM frequency in Hz

Note

This function is currently not implemented

Todo

Implement frequency change functionality

hal_pwm_start()

void hal_pwm_start

(

PWM_Handle *

pwm

)

Start PWM output.

Start PWM signal generation.

Parameters

[in]

pwm

Pointer to initialized PWM handle structure

Enables the timer counter to start generating PWM signals on the configured channel. The output will appear on the corresponding GPIO pin.

hal_pwm_stop()

void hal_pwm_stop

(

PWM_Handle *

pwm

)

Stop PWM output.

Stop PWM signal generation.

Parameters

[in]

pwm

Pointer to PWM handle structure

Disables the timer channel output and stops the timer counter. The PWM output pin will return to its idle state.