app_sched_execute followed by sd_app_evt_wait

Question

Hello, 
 I am working on a project based on the nRF51822 with the softdevice S110. 
 I am trying to develop an application using the main loop provided in an example application: 
 // Enter main loop
for (;;)
{
 app_sched_execute();
 <<-- interrupt raised here that calls app_sched_event_put
 sd_app_evt_wait();
}
 
 I am puzzled by this code for the idle loop, I do not understand how the system handles a situation where an interrupt is raised between the execution of app_shed_execute and sd_app_evt_wait. If the interrupt invokes a app_sched_event_put, then the system will still go to (deep) sleep mode and will not execute the event handler until the next loop which could come much later.
Am I missing something in the architecture? 
 Thanks
Louis

Nikita · Accepted Answer

Did you read this? 
 /**@brief Waits for an application event.
 * 
 * An application event is either an application interrupt or a pended interrupt when the
 * interrupt is disabled. When the interrupt is enabled it will be taken immediately since
 * this function will wait in thread mode, then the execution will return in the application's
 * main thread. When an interrupt is disabled and gets pended it will return to the application's 
 * thread main. The application must ensure that the pended flag is cleared using 
 * ::sd_nvic_ClearPendingIRQ in order to sleep using this function. This is only necessary for
 * disabled interrupts, as the interrupt handler will clear the pending flag automatically for
 * enabled interrupts.
 *
 * In order to wake up from disabled interrupts, the SEVONPEND flag has to be set in the Cortex-M0
 * System Control Register (SCR). @sa CMSIS_SCB
 *
 * @note If an application interrupt has happened since the last time sd_app_evt_wait was
 * called this function will return immediately and not go to sleep. This is to avoid race
 * conditions that can occur when a flag is updated in the interrupt handler and processed
 * in the main loop.
 *
 * @post An application interrupt has happened or a interrupt pending flag is set.
 *
 * @retval ::NRF_SUCCESS
 */
SVCALL(SD_APP_EVT_WAIT, uint32_t, sd_app_evt_wait(void));

app_sched_execute followed by sd_app_evt_wait

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