Simple Task Scheduler - LUFA/Scheduler/Scheduler.h


Data Structures

struct  TaskEntry_t

Defines

#define TASK(name)   void name (void)
#define TASK_LIST   TaskEntry_t Scheduler_TaskList[] =
#define TASK_MAX_DELAY   (MAX_DELAYCTR_COUNT - 1)
#define TASK_RUN   true
#define TASK_STOP   false

Typedefs

typedef void(* TaskPtr_t )(void)
typedef uint16_t SchedulerDelayCounter_t

Functions

void Scheduler_Start (void)
void Scheduler_Init (void)
static void Scheduler_ResetDelay (SchedulerDelayCounter_t *const DelayCounter) ATTR_NON_NULL_PTR_ARG(1) ATTR_ALWAYS_INLINE
bool Scheduler_HasDelayElapsed (const uint16_t Delay, SchedulerDelayCounter_t *const DelayCounter) ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(2)
void Scheduler_SetTaskMode (const TaskPtr_t Task, const bool TaskStatus)
void Scheduler_SetGroupTaskMode (const uint8_t GroupID, const bool TaskStatus)

Variables

TaskEntry_t Scheduler_TaskList []
volatile uint8_t Scheduler_TotalTasks
volatile SchedulerDelayCounter_t Scheduler_TickCounter

Detailed Description

Deprecated:
This module is deprecated and will be removed in a future library release.

Module Source Dependencies

The following files must be built with any user project that uses this module:

Description

Simple round-robbin cooperative scheduler for use in basic projects where non real-time tasks need to be executed. Each task is executed in sequence, and can be enabled or disabled individually or as a group.

For a task to yield it must return, thus each task should have persistent data marked with the static attribute.

Usage Example:

      #include <LUFA/Scheduler/Scheduler.h>
      
      TASK(MyTask1);
      TASK(MyTask2);
      
      TASK_LIST
      {
        { .Task = MyTask1, .TaskStatus = TASK_RUN, .GroupID = 1  },
        { .Task = MyTask2, .TaskStatus = TASK_RUN, .GroupID = 1  },
      }

      int main(void)
      {
        Scheduler_Start();
      }

      TASK(MyTask1)
      {
        // Implementation Here
      }

      TASK(MyTask2)
      {
        // Implementation Here
      }

Define Documentation

#define TASK ( name   )     void name (void)

Creates a new scheduler task body or prototype. Should be used in the form:

      TASK(TaskName); // Prototype

      TASK(TaskName)
      {
           // Task body
      }

#define TASK_LIST   TaskEntry_t Scheduler_TaskList[] =

Defines a task list array, containing one or more task entries of the type TaskEntry_t. Each task list should be encased in curly braces and ended with a comma.

Usage Example:

      TASK_LIST
      {
           { .Task = MyTask1, .TaskStatus = TASK_RUN, .GroupID = 1 },
           // More task entries here
      }

#define TASK_MAX_DELAY   (MAX_DELAYCTR_COUNT - 1)

Constant, giving the maximum delay in scheduler ticks which can be stored in a variable of type SchedulerDelayCounter_t.

#define TASK_RUN   true

Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode().

#define TASK_STOP   false

Task status mode constant, for passing to Scheduler_SetTaskMode() or Scheduler_SetGroupTaskMode().


Typedef Documentation

typedef uint16_t SchedulerDelayCounter_t

Type define for a variable which can hold a tick delay value for the scheduler up to the maximum delay possible.

typedef void(* TaskPtr_t)(void)

Type define for a pointer to a scheduler task.


Function Documentation

bool Scheduler_HasDelayElapsed ( const uint16_t  Delay,
SchedulerDelayCounter_t *const   DelayCounter 
)

Determines if the given tick delay has elapsed, based on the given .

Parameters:
[in] Delay The delay to test for, measured in ticks
[in] DelayCounter The counter which is storing the starting tick value for the delay
Returns:
Boolean true if the delay has elapsed, false otherwise
Usage Example:
      static SchedulerDelayCounter_t DelayCounter = 10000; // Force immediate run on start-up
                 
      // Task runs every 10000 ticks, 10 seconds for this demo
      if (Scheduler_HasDelayElapsed(10000, &DelayCounter))
      {
           // Code to execute after delay interval elapsed here
      }

void Scheduler_Init ( void   ) 

Initializes the scheduler so that the scheduler functions can be called before the scheduler itself is started. This must be executed before any scheduler function calls other than Scheduler_Start(), and can be omitted if no such functions could be called before the scheduler is started.

static void Scheduler_ResetDelay ( SchedulerDelayCounter_t *const   DelayCounter  )  [inline, static]

Resets the delay counter value to the current tick count. This should be called to reset the period for a delay in a task which is dependant on the current tick value.

Parameters:
[out] DelayCounter Counter which is storing the starting tick count for a given delay.

void Scheduler_SetGroupTaskMode ( const uint8_t  GroupID,
const bool  TaskStatus 
)

Sets the task mode for a given task group ID, allowing for an entire group of tasks to have their statuses changed at once.

Parameters:
[in] GroupID Value of the task group ID whose status is to be changed
[in] TaskStatus New task status for tasks in the specified group (TASK_RUN or TASK_STOP)

void Scheduler_SetTaskMode ( const TaskPtr_t  Task,
const bool  TaskStatus 
)

Sets the task mode for a given task.

Parameters:
[in] Task Name of the task whose status is to be changed
[in] TaskStatus New task status for the task (TASK_RUN or TASK_STOP)

void Scheduler_Start ( void   ) 

Starts the scheduler in its infinite loop, executing running tasks. This should be placed at the end of the user application's main() function, as it can never return to the calling function.


Variable Documentation

Task entry list, containing the scheduler tasks, task statuses and group IDs. Each entry is of type TaskEntry_t and can be manipulated as desired, although it is preferential that the proper Scheduler functions should be used instead of direct manipulation.

Contains the current scheduler tick count, for use with the delay functions. If the delay functions are used in the user code, this should be incremented each tick period so that the delays can be calculated.

volatile uint8_t Scheduler_TotalTasks

Contains the total number of tasks in the task list, irrespective of if the task's status is set to TASK_RUN or TASK_STOP.

Note:
This value should be treated as read-only, and never altered in user-code.


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