Queries on Application Timer functionality

Question

Hello, 
 
 I am using nRF52832, SDK_15.3.0, S132 SoftDevice and Segger for flash the image. I am using ‘ble_app_blinky’. 
 
 I have gone through “Application Timer” tutorial. 
 https://devzone.nordicsemi.com/nordic/tutorials/b/software-development-kit/posts/application-timer-tutorial 
 
 I have few queries. 
 
 1) Using “Application Timer module” how many max timers / handlers can be executed at a time with APP_TIMER_MODE_REPEATED. At application level I need 5 timers. Since RTC1 has CC[0..3] whether I can use only 4 at a time. 
 
 a) Whether APP_TIMER_CONFIG_OP_QUEUE_SIZE is for that purpose only ?

2) I want to sleep & wakeup periodically for every 30 minutes. For this I need to change PRESCALER. To my understanding there will be only one prescaler for entire timer module. So if I change, will there be any impact on existing timers and SoftDevice (Not sure whether SoftDevice uses Application Timer). 
 
 3) I want to stop LED after 10 blink automatically. In this case with some conditions whether can I call app_timer_stop() within same handler (repeated_timer_handler()). 
 static void repeated_timer_handler(void * p_context)
{

 :
 :

 err_code = app_timer_stop(m_repeated_timer_id);
 APP_ERROR_CHECK(err_code);
 
 :
} 
 
 4) Whether handler will execute in Interrupt context. I want to read data over TWI and write data into Flash. Whether all there can be called within timer handler. 
 static void repeated_timer_handler_1(void * p_context)
{
 :
 
 // Read sensor data.
 
 :
 :
 
 // Write data into Flash
 nrf_fstorage_write( ... );
 
 :
 :
} 
 
 Thanks & Regards 
 Vishnu Beema

Simon · Accepted Answer

1) Using “Application Timer module” how many max timers / handlers can be executed at a time with APP_TIMER_MODE_REPEATED. At application level I need 5 timers. Since RTC1 has CC[0..3] whether I can use only 4 at a time. 
 I am not sure what the maximum amount of timers are, and what the limiting factor is, but I tried adding 6 timers to an application and that worked fine. I don't think APP_TIMER_CONFIG_OP_QUEUE_SIZE is the limiting factor, since I set it to 1 and all the 6 timers still fires. I can look into it further if you would like a more precise answer. 
 
 2) I want to sleep & wakeup periodically for every 30 minutes. For this I need to change PRESCALER. To my understanding there will be only one prescaler for entire timer module. So if I change, will there be any impact on existing timers and SoftDevice (Not sure whether SoftDevice uses Application Timer). 
 The APP_TIMER_CONFIG_RTC_FREQUENCY (RTC prescaler) is not used by the Softdevice 
 
 3) I want to stop LED after 10 blink automatically. In this case with some conditions whether can I call app_timer_stop() within same handler (repeated_timer_handler()). 
 No problem, you can do this 
 
 4) Whether handler will execute in Interrupt context. I want to read data over TWI and write data into Flash. Whether all there can be called within timer handler. 
 This shouldn’t be a problem 
 
 Best regards, 
 Simon

Queries on Application Timer functionality

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