Hello
I'm using a passive buzzer controlled by PWM.
When PWM is set and run, the buzzer will continue to output small noises.
This is probably a code problem. Below is my PWM code
#include "app_pwm.h"
APP_PWM_INSTANCE(PWM1,1); // Create the instance "PWM1" using TIMER1 (name, NRF_DRV_TIMER_INSTANCE(num)).
void pwm_play_buzzer_duration(uint32_t duration) //button buzzer
{
uint8_t i;
uint32_t duty = 50;
NRF_LOG_INFO("pwm_play_buzzer_duration =>");
ready_flag = false;
//Set the duty cycle - keep trying until PWM is ready...
while (app_pwm_channel_duty_set(&PWM1, 0, duty) == NRF_ERROR_BUSY);
// ... or wait for callback.
//while (!ready_flag);
//APP_ERROR_CHECK(app_pwm_channel_duty_set(&PWM1, 1, duty));
nrf_delay_ms(duration);
app_pwm_disable(&PWM1);
}
void pwm_ready_callback(uint32_t pwm_id) // PWM callback function
{
NRF_LOG_INFO("pwm_ready_callback =>");
ready_flag = true;
}
/*
init, Once executed
*/
//buzzer PWM initializing
void pwm_init(void)
{
ret_code_t err_code;
/* 1-channel PWM, 200Hz, output on DK LED pins. */
app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(1500, BUZZER_PIN); //original 5000L
/* Switch the polarity of the second channel. */
pwm1_cfg.pin_polarity[1] = APP_PWM_POLARITY_ACTIVE_HIGH;
/* Initialize and enable PWM. */
err_code = app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM1);
printf("Start PWM\n");
}
/*
pwm_change_frequency,Can be executed multiple times
*/
void pwm_change_frequency(uint16_t period_us) // ex) pwm_change_frequency(500);
{
ret_code_t err_code;
app_pwm_disable(&PWM1); //disable PWM for change PWM
app_pwm_uninit(&PWM1); //uninitializing a PWM
/* 1-channel PWM, 200Hz, output on DK LED pins. */
app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(period_us, BUZZER_PIN); //original 5000L
/* Switch the polarity of the second channel. */
pwm1_cfg.pin_polarity[1] = APP_PWM_POLARITY_ACTIVE_HIGH;
/* Initialize and enable PWM. */
err_code = app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM1);
}
static void do_play_buzzer(void)
{
pwm_play_buzzer_duration(200); //buzzer play time
app_pwm_enable(&PWM1);
//printf("Play buzzer\n");
}
What is the PWM noise related to?
Thank you.
