52832 PWM delay

RE: 52832 PWM delay

Jared — Wed, 22 May 2019 14:28:05 GMT

Hi,

I've included a screenshot of the measured delay between the pin set and the PWM signal being produced on the pin. The only difference is the change in period from 250 µs to 10 µs. I used your code but configured it a bit to get a more accurate measurement

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "app_error.h"
#include "bsp.h"
#include "nrf_delay.h"
#include "app_pwm.h"

APP_PWM_INSTANCE(PWM0,1);                   // Â´Â´Â½Â¨Ã’Â»Â¸Ã¶ÃŠÂ¹Ã“ÃƒÂ¶Â¨ÃŠÂ±Ã†Ã·1Â²ÃºÃ‰ÃºPWMÂ²Â¨ÂµÃ„ÃŠÂµÃ€Ã½

static volatile bool ready_flag;            // ÃŠÂ¹Ã“ÃƒÃ’Â»Â¸Ã¶Â±ÃªÃ–Â¾ÃŽÂ»Â±ÃÃŠÂ¾PWMÃ—Â´ÃŒÂ¬

void pwm_ready_callback(uint32_t pwm_id)    // PWMÂ»Ã˜ÂµÃ·Â¹Â¦Ã„Ãœ
{
    ready_flag = true;
}

void ADC_PWM_START(void)
{
	app_pwm_enable(&PWM0);
	while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);
	nrf_gpio_pin_set(16);
}

void ADC_PWM_STOP(void)
{
	app_pwm_disable(&PWM0);
	nrf_gpio_pin_clear(16);
}

int main(void)
{
    ret_code_t err_code;
    
    /* 2-Â¸Ã¶Ã†ÂµÂµÃ€ÂµÃ„ PWM, 200HzÂ£Â¨5000us=5ms), ÃÂ¨Â¹Ã½ Â¿ÂªÂ·Â¢Â°Ã¥LED Â¹ÃœÂ½Ã…ÃŠÃ¤Â³Ã¶. */
    app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(10, 26);
    
    /* Ã‡ÃÂ»Â»ÃÂ½Â¸Ã¶Ã†ÂµÂµÃ€ÂµÃ„Â¼Â«ÃÃ” */
    pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_HIGH;
    
    /* Â³ÃµÃŠÂ¼Â»Â¯ÂºÃÃŠÂ¹Ã„ÃœPWM. */
    err_code = app_pwm_init(&PWM0,&pwm1_cfg,NULL);
    APP_ERROR_CHECK(err_code);
    nrf_gpio_cfg_output(4);
    app_pwm_enable(&PWM0);//ÃŠÂ¹Ã„ÃœPWM
   		
            
		/* Ã‰Ã¨Ã–ÃƒÃ•Â¼Â¿Ã•Â±Ãˆ - Â²Â»ÃÂ£Ã‰Ã¨Ã–ÃƒÃ–Â±ÂµÂ½PWMÃ—Â¼Â±Â¸ÂºÃƒ. */
		while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);  
		/* ÂµÃˆÂ´Ã½Â»Ã˜ÂµÃ· */
		//nrf_delay_ms(25);
		nrf_gpio_pin_set(4);
	
   /* while(true)
    {
				nrf_delay_ms(1);
				ADC_PWM_STOP();
				nrf_delay_ms(1);
        ADC_PWM_START();							
    }*/
    
}

Regards

Jared

RE: 52832 PWM delay

NORDIC_SUR — Wed, 15 May 2019 05:17:44 GMT

"decrease the period to 10 µs from 50 µs" is meant to modify this code "while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);" is right?

but I cant found the "delay" is decreased.

RE: 52832 PWM delay

NORDIC_SUR — Wed, 15 May 2019 05:16:46 GMT

"decrease the period to 10 µs from 50 µs" is meant to modify this code "while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);" is right?

but I cant found the "delay" is decreased.

RE: 52832 PWM delay

Jared — Wed, 08 May 2019 07:54:24 GMT

Hi,

Sorry, I meant if you decrease the period to 10 µs from 50 µs, you will see that the "delay" between the function call and the produced signal is decreased.

You should also modify your code before testing to easier highlight the difference. Initializing of the pin and the delay should either be removed to an earlier point in the code or removed.

Best regards

Jared

RE: 52832 PWM delay

NORDIC_SUR — Mon, 06 May 2019 14:40:02 GMT

sorry,I dont kown what you mean to reduce the period to 10.

RE: 52832 PWM delay

Jared — Mon, 06 May 2019 13:54:01 GMT

Hi,

The added delay is a result of the prolonged period. You can see this yourself by reducing the period to 10 for example.It should then take shorter time for the signal to be produced on the GPIO. It's not a delay per se, but a consequence of a bigger period.

Jared

RE: 52832 PWM delay

NORDIC_SUR — Tue, 30 Apr 2019 01:51:44 GMT

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "app_error.h"
#include "bsp.h"
#include "nrf_delay.h"
#include "app_pwm.h"

APP_PWM_INSTANCE(PWM0,1);                   // ´´½¨Ò»¸öÊ¹ÓÃ¶¨Ê±Æ÷1²úÉúPWM²¨µÄÊµÀý

static volatile bool ready_flag;            // Ê¹ÓÃÒ»¸ö±êÖ¾Î»±íÊ¾PWM×´Ì¬

void pwm_ready_callback(uint32_t pwm_id)    // PWM»Øµ÷¹¦ÄÜ
{
    ready_flag = true;
}

void ADC_PWM_START(void)
{
	app_pwm_enable(&PWM0);
	while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);
	nrf_gpio_pin_set(16);
}

void ADC_PWM_STOP(void)
{
	app_pwm_disable(&PWM0);
	nrf_gpio_pin_clear(16);
}

int main(void)
{
    ret_code_t err_code;
    
    /* 2-¸öÆµµÀµÄ PWM, 200Hz£¨5000us=5ms), Í¨¹ý ¿ª·¢°åLED ¹Ü½ÅÊä³ö. */
    app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(250, 26);
    
    /* ÇÐ»»Á½¸öÆµµÀµÄ¼«ÐÔ */
    pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_HIGH;
    
    /* ³õÊ¼»¯ºÍÊ¹ÄÜPWM. */
    err_code = app_pwm_init(&PWM0,&pwm1_cfg,NULL);
    APP_ERROR_CHECK(err_code);
    app_pwm_enable(&PWM0);//Ê¹ÄÜPWM
   		
            
		/* ÉèÖÃÕ¼¿Õ±È - ²»Í£ÉèÖÃÖ±µ½PWM×¼±¸ºÃ. */
		while (app_pwm_channel_duty_set(&PWM0, 0, 0) == NRF_ERROR_BUSY);  
		/* µÈ´ý»Øµ÷ */
		nrf_delay_ms(25);
		nrf_gpio_cfg_output(16);
		nrf_gpio_pin_set(16);
	
    while(true)
    {
				nrf_delay_ms(1);
				ADC_PWM_STOP();
				nrf_delay_ms(1);
        ADC_PWM_START();								
    }
    
}

my code like this.it's diferent with your.please test my code on your circuit.thaks

RE: 52832 PWM delay

Jared — Mon, 29 Apr 2019 13:15:51 GMT

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "app_error.h"
#include "bsp.h"
#include "nrf_delay.h"
#include "app_pwm.h"

APP_PWM_INSTANCE(PWM1,1);                   // Create the instance "PWM1" using TIMER1.

static volatile bool ready_flag;            // A flag indicating PWM status.

void pwm_ready_callback(uint32_t pwm_id)    // PWM callback function
{

}

int main(void)
{
ret_code_t  err_code;
uint16_t value = 0XFF;

app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(10,3);
pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_HIGH;
nrf_gpio_cfg_output(4);
nrf_gpio_pin_clear(4);



err_code = app_pwm_init(&PWM1,&pwm1_cfg, pwm_ready_callback);
APP_ERROR_CHECK(err_code);
app_pwm_enable(&PWM1);
while (app_pwm_channel_duty_set(&PWM1, 0, value) == NRF_ERROR_BUSY);
nrf_gpio_pin_set(4);


while(true)
{
}

}

RE: 52832 PWM delay

NORDIC_SUR — Mon, 29 Apr 2019 07:41:23 GMT

if I set pwm like this "while (app_pwm_channel_duty_set(&PWM0, 0, 100) == NRF_ERROR_BUSY)",the delay time only 2.2us.why have all this strange phenomena

RE: 52832 PWM delay

NORDIC_SUR — Mon, 29 Apr 2019 07:18:08 GMT

I use the SDK_15.0.0/PWM_library project to do the same thing,it also have the same bug.

RE: 52832 PWM delay

NORDIC_SUR — Mon, 29 Apr 2019 03:54:41 GMT

I try some test today.

1. if I set the pwm frequence like this APP_PWM_DEFAULT_CONFIG_1CH(250L, PWM_PIN);the delay time is about 250us

2. APP_PWM_DEFAULT_CONFIG_1CH(2500L, PWM_PIN),the delay time is about 2500us;

3. APP_PWM_DEFAULT_CONFIG_1CH(4000L, PWM_PIN),the delay time is about 4000us;

so it look like I don't diable some register,which cause a pwm delay.

RE: 52832 PWM delay

NORDIC_SUR — Mon, 29 Apr 2019 03:13:49 GMT

I find that only use PWM ,not use ble stack.it also need to wait 200us before 52832 product pwm.can you send your code for me?

RE: 52832 PWM delay

NORDIC_SUR — Sun, 28 Apr 2019 12:16:10 GMT

I find that I need to wait about 100us before 52832 stop pwm

RE: 52832 PWM delay

NORDIC_SUR — Sun, 28 Apr 2019 11:16:19 GMT

I use the PWM on the ble protocol stack.can you help me to try it on the ble protocol stack?

RE: 52832 PWM delay

Jared — Thu, 25 Apr 2019 11:13:58 GMT

Hi,

I reproduced the measurement and measured 2.63 µs. Are you doing something else in your code besides using the pwm?

Best regards

Jared

RE: 52832 PWM delay

NORDIC_SUR — Wed, 24 Apr 2019 09:53:53 GMT

Hi, Jared.

thank you for your answer.

I set pin17 to output high level after "while (app_pwm_channel_duty_set(&PWM0, 0, 50) == NRF_ERROR_BUSY);"

and then set pin17 output low level after I disable the PWM.

RE: 52832 PWM delay

Jared — Wed, 24 Apr 2019 08:58:48 GMT

Hi,

Could you explain your measurement setup a bit more in detail?

Are you measuring from the moment the CPU boots until the PWM signal is produced?
Or are you measuring from the moment the function PWM_start() is called and until the PWM signal is produced?

If it's the latter, how are you signaling that the function PWM_start() is called?

Best regards

Jared