how can i use pwm?
Posted: Fri Nov 14, 2014 3:05 pmhow can i use pwm on gpio pins? anyone help me? anyone share simple pwm example?
For example you need to pin # by::
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#define PWM_0_OUT_IO_MUX PERIPHS_IO_MUX_GPIO2_U
#define PWM_0_OUT_IO_NUM 2
#define PWM_0_OUT_IO_FUNC FUNC_GPIO2
#define PWM_CHANNEL 1
PWM_CHANNEL 1 means you are gonna use only one PWM in your program.
in user_init, you can:
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uint8_t duty=0;
pwm_init( 150, &duty);
pwm_start();Than in anywhere to adjust PWM:
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pwm_set_duty(duty, 0);
pwm_start();You have to run pwm_start function after changing duty cycle.
Otherwise it doesn't run.
Here is sample code:
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#include <ets_sys.h>
#include <osapi.h>
#include <os_type.h>
#include <gpio.h>
#include "user_interface.h"
#define user_procTaskPrio 0
#define user_procTaskQueueLen 1
os_event_t user_procTaskQueue[user_procTaskQueueLen];
// see eagle_soc.h for these definitions
#define PWM_0_OUT_IO_MUX PERIPHS_IO_MUX_GPIO2_U
#define PWM_0_OUT_IO_NUM 2
#define PWM_0_OUT_IO_FUNC FUNC_GPIO2
#define PWM_CHANNEL 1
LOCAL uint8_t led_state=0;
LOCAL uint8_t duty=0;
//Main code function for heartbeat LED on GPIO2
void ICACHE_FLASH_ATTR
loop(os_event_t *events)
{
os_delay_us(10000);
led_state ? duty-- : duty++;
if (duty >= 255 ) led_state=1;
else if (duty <= 10 ) led_state=0;
pwm_set_duty(duty, 0);
pwm_start();
system_os_post(user_procTaskPrio, 0, 0 );
}
void user_init(void)
{
pwm_init( 150, &duty);
pwm_start();
//Start os task
system_os_task(loop, user_procTaskPrio,user_procTaskQueue, user_procTaskQueueLen);
system_os_post(user_procTaskPrio, 0, 0 );
}