nRF51 SDK - S120 SoftDevice
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The scheduler is used for transferring execution from the interrupt context to the main context. More...

Macros

#define APP_SCHED_EVENT_HEADER_SIZE   8
 
#define APP_SCHED_BUF_SIZE(EVENT_SIZE, QUEUE_SIZE)   (((EVENT_SIZE) + APP_SCHED_EVENT_HEADER_SIZE) * ((QUEUE_SIZE) + 1))
 Compute number of bytes required to hold the scheduler buffer. More...
 
#define APP_SCHED_INIT(EVENT_SIZE, QUEUE_SIZE)
 Macro for initializing the event scheduler. More...
 

Typedefs

typedef void(* app_sched_event_handler_t )(void *p_event_data, uint16_t event_size)
 Scheduler event handler type.
 

Functions

uint32_t app_sched_init (uint16_t max_event_size, uint16_t queue_size, void *p_evt_buffer)
 Function for initializing the Scheduler. More...
 
void app_sched_execute (void)
 Function for executing all scheduled events. More...
 
uint32_t app_sched_event_put (void *p_event_data, uint16_t event_size, app_sched_event_handler_t handler)
 Function for scheduling an event. More...
 

Detailed Description

The scheduler is used for transferring execution from the interrupt context to the main context.

See Applications using the Scheduler for sequence diagrams illustrating the flow of events when using the Scheduler.

Requirements:

Logic in main context:

Logic in interrupt context:

For an example usage of the scheduler, please see the implementations of ble_sdk_app_hids_mouse and ble_sdk_app_hids_keyboard.

scheduler_working.jpg
The high level design of the scheduler

Macro Definition Documentation

#define APP_SCHED_BUF_SIZE (   EVENT_SIZE,
  QUEUE_SIZE 
)    (((EVENT_SIZE) + APP_SCHED_EVENT_HEADER_SIZE) * ((QUEUE_SIZE) + 1))

Compute number of bytes required to hold the scheduler buffer.

Parameters
[in]EVENT_SIZEMaximum size of events to be passed through the scheduler.
[in]QUEUE_SIZENumber of entries in scheduler queue (i.e. the maximum number of events that can be scheduled for execution).
Returns
Required scheduler buffer size (in bytes).
#define APP_SCHED_EVENT_HEADER_SIZE   8

Size of app_scheduler.event_header_t (only for use inside APP_SCHED_BUF_SIZE()).

#define APP_SCHED_INIT (   EVENT_SIZE,
  QUEUE_SIZE 
)
Value:
do \
{ \
static uint32_t APP_SCHED_BUF[CEIL_DIV(APP_SCHED_BUF_SIZE((EVENT_SIZE), (QUEUE_SIZE)), \
sizeof(uint32_t))]; \
uint32_t ERR_CODE = app_sched_init((EVENT_SIZE), (QUEUE_SIZE), APP_SCHED_BUF); \
APP_ERROR_CHECK(ERR_CODE); \
} while (0)

Macro for initializing the event scheduler.

It will also handle dimensioning and allocation of the memory buffer required by the scheduler, making sure the buffer is correctly aligned.

Parameters
[in]EVENT_SIZEMaximum size of events to be passed through the scheduler.
[in]QUEUE_SIZENumber of entries in scheduler queue (i.e. the maximum number of events that can be scheduled for execution).
Note
Since this macro allocates a buffer, it must only be called once (it is OK to call it several times as long as it is from the same location, e.g. to do a reinitialization).

Function Documentation

uint32_t app_sched_event_put ( void *  p_event_data,
uint16_t  event_size,
app_sched_event_handler_t  handler 
)

Function for scheduling an event.

Puts an event into the event queue.

Parameters
[in]p_event_dataPointer to event data to be scheduled.
[in]event_sizeSize of event data to be scheduled.
[in]handlerEvent handler to receive the event.
Returns
NRF_SUCCESS on success, otherwise an error code.
void app_sched_execute ( void  )

Function for executing all scheduled events.

This function must be called from within the main loop. It will execute all events scheduled since the last time it was called.

uint32_t app_sched_init ( uint16_t  max_event_size,
uint16_t  queue_size,
void *  p_evt_buffer 
)

Function for initializing the Scheduler.

It must be called before entering the main loop.

Parameters
[in]max_event_sizeMaximum size of events to be passed through the scheduler.
[in]queue_sizeNumber of entries in scheduler queue (i.e. the maximum number of events that can be scheduled for execution).
[in]p_evt_bufferPointer to memory buffer for holding the scheduler queue. It must be dimensioned using the APP_SCHED_BUFFER_SIZE() macro. The buffer must be aligned to a 4 byte boundary.
Note
Normally initialization should be done using the APP_SCHED_INIT() macro, as that will both allocate the scheduler buffer, and also align the buffer correctly.
Return values
NRF_SUCCESSSuccessful initialization.
NRF_ERROR_INVALID_PARAMInvalid parameter (buffer not aligned to a 4 byte boundary).