nRF9160 Timer issue

[ephraim]

Dear Sir.

I am using the Timer of nRF916 .

In a simple project the timer is working fine ( see attached code ).

A buzzer is connected to PWM output pin 12.

I can here the Buzzer beeps as expected .

Fullscreen main.c Download

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */
#include <nrf9160.h>
#include <zephyr.h>
#include <device.h>
#include <drivers/pwm.h>
#include <drivers/gpio.h>

//#define LED		12
#define PWM_IO		12
struct device *pwm_dev;

/* 1000 msec = 1 sec */
#define SLEEP_TIME	100

struct k_timer bz_timer;

void bz_func(struct k_timer *timer_id) 
{      
    static unsigned char k = 0;
    static unsigned int time = 0;
 
     // Siren
//     if(time == 0)
//       pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0);
//     if(time == 10)
//      pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 200,0);
//     if(++time >= 20)
//       time = 0;

     // Short Beep
     if(time == 0)
       pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0);
     if(time == 7)
       pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 0,0);
     if(++time >= 100)
       time = 0;

     // Long Beep
//     if(time == 0)
//       pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0);
//     if(time == 20)
//       pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 0,0);
//     if(++time >= 150)
//       time = 0;

       // Train
//       if(k < 100)
//       {
//         if(time == 0)
//           pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0);
//         if(time == 5)
//           pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 0,0);
//         if(++time >= 20)
//         {
//           time = 0;
//           if(++k > 20) 
//            k = 100;
//         }
//       }
}

void main(void)
{
	u32_t cnt = 0;
	struct device *dev_io;
        

        printk("PWM Application has started!\r\n");

        pwm_dev = device_get_binding("PWM_0");     
        if (!pwm_dev) {
		printk("Cannot find %s!\n", "PWM_0");        
		return;
	}

        k_timer_init(&bz_timer, bz_func, NULL);
        k_timer_start(&bz_timer, K_SECONDS(1), K_MSEC(50));

        while(1)
        {
            k_sleep(K_MSEC(800));
        }
}

In another larger project , I insert the Timer code , and it behaves erratically .

The time between each entry to the timer is seconds.

What can cause this behavior ?.

Please Advise

struct k_timer bz_timer;


void bz_func(struct k_timer *timer_id) 
{
  
    unsigned char k;
     static unsigned int time = 0;

   
     // Siren
     if(time == 0)
       pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0);
     if(time == 10)
      pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 200,0);
     if(++time >= 20)
       time = 0;

}


void main(void)
{
      int err;
      static unsigned int i = 0;

 
      k_work_init(&work_top, work_top_func);
      k_work_init(&work_spi, spi_work_func);    
      k_work_init(&work_adp5360, adp5360_work_func);

     

      initStructures();
       // Ephraim 26_5_2020
       _AFE4900_AQUIRE_MODE.aquire_mode =  afe4900_aquire_sample;

      k_timer_init(&bz_timer, bz_func, NULL);
      k_timer_start(&bz_timer, K_SECONDS(1), K_MSEC(50));

  
      io_init();
      pwm_init();
      
 
      while(1) {
 
          k_sleep(K_MSEC(2000));
   
          k_sleep(K_MSEC(2000));
   
    
      };

[Håkon Alseth]

Hi,

  

In another larger project , I insert the Timer code , and it behaves erratically .

What do you mean by this? Does it stop working after a while? Or does it not update the pwm value?

I see that you're not checking the return of the call to pwm_pin_set_usec. Please implement a check on the return code to ensure that the value has been set properly.

 

Kind regards,

Håkon 

[ephraim]

Hi.

I found the culprit  , 

void bz_func(struct k_timer *timer_id) 
{
   // k_work_submit(&work_bz);       
    unsigned char k;
     static unsigned int time = 0;
  //    SetLed(BLUE,ON);  
     k = _BZ_SM.bz_state;
     printk("Buzzer \n");
     // Siren
     if(time == 0)
     {
//      if(pwm_pin_set_usec(pwm_dev,PWM_IO, 260, 130,0) == 0)
      {
        SetLed(BLUE,ON); 
        SetLed(GREEN,OFF);
      }
//      else
//      {
//        SetLed(RED,ON);
//        printk("Buzzer Error\n");
//      }
     }


     if(time == 10)
     {
//      if(pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 200,0) == 0)
      {
        SetLed(BLUE,OFF); 
       SetLed(GREEN,ON); 
     }
//      else
//      {
//        SetLed(RED,ON);
//        printk("Buzzer Error\n");
//      }
     }
     if(++time >= 20)
       time = 0;

}

The Timer works fine without the update of the PWM .

When the PWM is re commented , the program reset itself ( see pic ).

The same code works fine in another small project .

Please Advise

[Håkon Alseth]

Hi,

 

The pwm zephyr wrapper for nRF devices is found in pwm_nrfx.c.

I cannot say what is wrong in your case, but the k_timer is inherited from the RTC interrupt handler, and the PWM module also relies on interrupts/events when setting the pin.

Can you try to use a workqueue instead of handling the PWM calls in the k_timer event handler?

 

You can read about workqueues here:

https://docs.zephyrproject.org/1.9.0/kernel/threads/workqueues.html

 

Kind regards,

Håkon

[ephraim]

Hi.

I am sorry , I am not following you.

Weather I use the workqueue , I will need to use the Timer.

Is it possible to produce interrupts without the timer ?.

if(time == 10)
{
// if(pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 200,0) == 0)
{
SetLed(BLUE,OFF);
SetLed(GREEN,ON);
}

It is the pwm_pin_set_usec(pwm_dev,PWM_IO, 400, 200,0) that make the reset .

[Håkon Alseth]

You should not call functions that take long time or rely on other interrupts from a k_timer handler, as its also in interrupt context.

 

If you use a work queue, you schedule the function to another context to avoid this scenario, just as described in the work queues documentation:

https://docs.zephyrproject.org/1.9.0/kernel/threads/workqueues.html

 

Kind regards,

Håkon