App_timer. Is it advisable to use app_timer with application when soft device is enabled.

[AimHigh]

Hi,

Good Day!

Statement of problem: Currently we are using app_timer in our application for conducting the user behavior. For example, for user input off of capacitive touch sensor we have used app_timer to model the user behavior. Also the RTC 2 is used for the device turn on, off, pair up mode and factory reset mode.And it is working as expected for now. Soft device is used in our application and we are yet to test it out.

Query: Is it advisable to use app_timer with the application (2 app_timer instances are used in our application) when the soft device is enabled?

If yes, How many app_timer instances one can use when the soft device is enabled and any measures to be taken while using the app_timer with soft device enabled?

If no, i.e. app_timer cannot be used with application when soft device is enabled, then what is best approach to implement this?

Kindly share any suggestions.

[haakonsh]

You can use two app_timers if you use RTC1 and RTC2, RTC0 is reserved by the SoftDevice. 

Do note that the app_timer is interrupt-driven and the SoftDevice's time-critical processes will have execution priority over the peripheral interrupts. This means that you will at times have app_timer events that have been blocked for a few ms. 

If this is a problem I suggest you try to offload the CPU with the PPI system (peripheral tasks/events) for your timing-critical stuff. 

[AimHigh]

Hi Haakonsh,

Thank you for your response. Now i get it, about app_timer with application. Certainly app_timer used for our application is having minimum timeout value of 80mSec. and I hope it would not make much of difference in adding +5~10 mSec as a delay to the application becasue of soft device. 

We do not have app_timer dealing with critical stuff.

[haakonsh]

That should be fine :)