Question about stopping all the timers that are used in the application.

[Rajat]

Hi Everyone

I have got 3 timers in my application. 

1 is repeated , and other two are Single shot which are ran from the inputs to the 1st Repeated timer.

The repeated keeps checking the UART for a byte , once the byte is received , One single shot timer is started , which on expiry turn One of my sensor OFF and inside the handler starts another single shot timer which again turns ON the sensor after 1 hour. 

If i stop the repeated timer when i turn OFF the Sensor , and start the Timer when I turn ON the sensor again. The whole thing just comes to a halt and it doesn't work anymore.

I have fixed this issue by using a timer of 10 seconds , which does literally nothing but keep repeating after 10 seconds, but i am not sure if the theory is correct or not.

""If all the timers have been turned OFF , the RTC goes to deep-sleep and it doesn't count anymore and to keep the RTC alive , i have used a repeated timer as desribed above.

It works in this configuration , but i am not sure if the reasoning is correct or not.""

Kindly help me understand this behavior.

Thanks 

Rajat

[Edvin]

Hello. Depending on the setup of your app_timer (mainly the prescaler value), you have to check whether your timeout is larger than half of the maximum timeout value.

The app_timer is a quite complex, and a limitation is that you need a timeout of less than half of the maximum timeout value.

What SDK version do you use? (just want to know so that we are looking at the same implementation of app_timer).

Best regards,

Edvin

[Rajat]

And from where can i find the maximum timeout value of an app_timer?

[Edvin]

Hello,

This depends on the prescaler that you use in your app_timer. The limit is the number of ticks you can use in the timeout. Since the app_timer uses the RTC, which is a 24bit counter/clock, you can maximum use a 23bit timeout tick value. This means that the maximum number of ticks you can use is 8388607 (0x7F FFFF).

Best regards,

Edvin

[Rajat]

okay , but 10 minute of duration is surely less than the the maximum timeout value. And so is 1 hour (3600000) . But it doesn't seem to be working without the workaround

[Rajat]

And what is the dependency of timer value on prescaler .

Could you just guide me to some document related to this query or similar?