inner and outer application timers, is it a problem?

[control]

Hi everyone,

I have one problem with the application timer. When I change the state of characteristic to the value of 1, the following code is executed:

   err_code = app_timer_stop(m_mass_timer_id);        					   
   p_mass->load_cell_calibration.flag_offset = 1; 				
   err_code = app_timer_start(m_mass_timer_id, MASS_MEAS_100MS_INTERVAL ,NULL);
   APP_ERROR_CHECK(err_code);        			   			   					
    			

The m_mass_timer_id handler is defined as:

    static void mass_timer_handler(void * p_context)
    { 

  uint8_t          err_code; 
  	
	  
		if(m_mass.mass_flag == 1) 
		{											
				
				m_mass.mass_flag = 0;

				err_code = app_timer_start(m_mass_one_cycle_timer_id, MASS_MEAS_30MS_INTERVAL, NULL);
				APP_ERROR_CHECK(err_code);
				SEGGER_RTT_WriteString(0, "MASS_TIMER\n");
				err_code = app_timer_start(m_mass_timer_id, MASS_MEAS_INTERVAL, NULL);
				APP_ERROR_CHECK(err_code);							
							
					
		}		
		else
		{
			SEGGER_RTT_WriteString(0, "MISTAKE\n");
		}	
	
}              			
    				

where m_mass_one_cyler_timer is executed by the following code:

static void mass_one_cycle_timer_handler(void * p_context)
{ 
	

	uint8_t err_code; 	

			if(m_mass.load_cell_calibration.flag_offset == 1)
			{
				
				err_code = ble_mgs_offset_load_cell_update(&m_mass,0); 			
        APP_ERROR_CHECK(err_code); 
								

        }

			m_mass.mass_flag = 1;			



}

If I change the state of characteristic a few times in a row, then the mass_timer_handler does not instantly execute but it holds on for a few seconds. I do not get any error and I do not know why this latency occurs. I am using SDK 10. The initialization of both timers are defined by the following code:

static void timers_init(void)
{
   
	  APP_TIMER_APPSH_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, true);
    uint8_t err_code;	

		
	  err_code = app_timer_create(&m_mass_timer_id, APP_TIMER_MODE_SINGLE_SHOT, mass_timer_handler);
	  APP_ERROR_CHECK(err_code);
//		
		err_code = app_timer_create(&m_mass_one_cycle_timer_id, APP_TIMER_MODE_SINGLE_SHOT, mass_one_cycle_timer_handler);
	  APP_ERROR_CHECK(err_code);
      	 
}

I would kindly appreciate your assistance on this issue.

Edit: A few minutes ago, I tested the program only with timer m_mass_timer_id I removed timer m_mass_one_cycle_timer_id, but I got the same problem as was described.

 static void mass_timer_handler(void * p_context)
        { 
    
               uint8_t          err_code;       	
    	  
    		if(m_mass.mass_flag == 1) 
    		{											
    				
    				if(m_mass.load_cell_calibration.flag_offset == 1)
    			{
    				
    				err_code = ble_mgs_offset_load_cell_update(&m_mass,0); 			
                               APP_ERROR_CHECK(err_code);    								
    
                       }      
    				
    				SEGGER_RTT_WriteString(0, "MASS_TIMER\n");
    				err_code = app_timer_start(m_mass_timer_id, MASS_MEAS_INTERVAL, NULL);
    				APP_ERROR_CHECK(err_code);							
    							
    					
    		}		
    		else
    		{
    			SEGGER_RTT_WriteString(0, "MISTAKE\n");
    		}	
    	
    }              	

	

I hope that I will get reply to my problem as fast as possible.

Thanks in advance.

Best regards Mike

[control]

I found the solution but I do not know why it works now. As presented in code above I used the scheduler for both timers. But this setting was not enough I also added the softdevice to scheduler ( SOFTDEVICE_HANDLER_APPSH_INIT(NRF_CLOCK_LFCLKSRC_XTAL_20_PPM, true);) and now everything works fine. I am wondering why I have to add the softdevice to schedurer. I will be really appreciated for any kind of explanation.

Mike

[MartinBL]

Not entirely sure if it is relevant, but restarting m_mass_timer_id inside its own handler like that could lead to troubles. As you can see here, app_timer_start(), if you call this method on a timer that is already running, the second start operation is ignored.

[MartinBL]

You can try to call app_timer_stop() before you start it again.

[control]

Thanks for this useful information. It makes sense now. I have one additional question which is somehow related to this topic. As I already mentioned I use the scheduler for softdevice and timers. It means that the timers are executed in the main loop. The code in timer usually ends with calling a pstorage function in which the calculated variables are stored. I do not know which of the following solutions are better one: 1) pstorage function is called directly from the timer (it is possible to do because the timer is executed in the main loop) or 2) to call the function app_sched_event_put() in timer and thus additional event is generated in the scheduler.

Thanks for help in advance Mike

[MartinBL]

I'm not sure if I understand. Are there any downsides of option 1 compared to option 2 at all? You are in the main context anyway and it sounds to me like option 1 will get the job done faster and with less code.