What is the point of app_scheduler.h in the ble eddystone example?

Question

The ble_app_eddystone example that comes with the SDK uses the scheduler, but I have failed to see where any handlers are registered to the scheduler (and grep -ing the eddystone library itself shows it uses the scheduler only in the flash-memory related logic). 
 I feel silly asking, but where in main.c is the scheduler told to do anything related to ble ? What needs to be changed so that the eddystone example can run without the scheduler library?

shibshab · Accepted Answer

The scheduler is used (as you state) for performing the garbage collection.
The app_timer library also uses the scheduler (see the APP_TIMER_CONFIG_USE_SCHEDULER config).
No BLE activity is directly controlled by the scheduler. 
 If you want to remove the scheduler dependency, implement some check in main-context whether or not garbage collection should be done, and change the config of app_timer to not use the scheduler.

Bjørn Kvaale · Answer

Hi Krastanov. The app_scheduler's primary function is to move any processing out of the interrupt handlers and into the main loop. The advantages of this are short interrupt handlers & all interrupts are dealth with ASAP ( see link ). In the main() function in the main.c file, the scheduler is initialized first. Afterwards, the function app_sched_execute() is run. This function executes all events scheduled since the last time it was called. 
 Regarding your question: "is the scheduler told to do anything related to ble?": It is true that no BLE activity is directly controlled by the scheduler. But in the eddystone example, the APP_TIMER_CONFIG_USE_SCHEDULER enables scheduling of app_timer to the app_scheduler . So essentially you use the scheduler to cycle through the different eddystone adversting frames. Therefore, you could say that the app_scheduler is indirectly used for BLE advertising. 
 It might also be useful to take a look at the Nordic Infocenter & this scheduler library link . This devzone case could also be useful, as well as taking a look at the scheduler tutorial .

What is the point of app_scheduler.h in the ble eddystone example?

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