http://www.freertos.org/a00110.html
FreeRTOS is customised using a configuration file called FreeRTOSConfig.h. Every FreeRTOS application must have a FreeRTOSConfig.h header file in its pre-processor include path. FreeRTOSConfig.h tailors the RTOS kernel to the application being built. It is therefore specific to the application, not the RTOS, and should be located in an application directory, not in one of the RTOS kernel source code directories.
Each demo application included in the RTOS source code download has its own FreeRTOSConfig.h file. Some of the demos are quite old and do not contain all the available configuration options. Configuration options that are omitted are set to a default value within an RTOS source file.
Here is a typical FreeRTOSConfig.h definition, followed by an explanation of each parameter:
#ifndef FREERTOS_CONFIG_H #define FREERTOS_CONFIG_H /* Here is a good place to include header files that are required across your application. */ #include "something.h"
// Set to 1 to use the preemptive RTOS scheduler, or 0 to use the cooperative RTOS scheduler. #define configUSE_PREEMPTION 1
#define configUSE_PORT_OPTIMISED_TASK_SELECTION 0 #define configUSE_TICKLESS_IDLE 0 #define configCPU_CLOCK_HZ 60000000 #define configTICK_RATE_HZ 250 #define configMAX_PRIORITIES 5 #define configMINIMAL_STACK_SIZE 128 #define configTOTAL_HEAP_SIZE 10240 #define configMAX_TASK_NAME_LEN 16 #define configUSE_16_BIT_TICKS 0 #define configIDLE_SHOULD_YIELD 1 #define configUSE_MUTEXES 0 #define configUSE_RECURSIVE_MUTEXES 0 #define configUSE_COUNTING_SEMAPHORES 0 #define configUSE_ALTERNATIVE_API 0 /* Deprecated! */ #define configQUEUE_REGISTRY_SIZE 10 #define configUSE_QUEUE_SETS 0 #define configUSE_TIME_SLICING 0 #define configUSE_NEWLIB_REENTRANT 0 /* Hook function related definitions. */ #define configUSE_IDLE_HOOK 0 #define configUSE_TICK_HOOK 0 #define configCHECK_FOR_STACK_OVERFLOW 0 #define configUSE_MALLOC_FAILED_HOOK 0 /* Run time and task stats gathering related definitions. */ #define configGENERATE_RUN_TIME_STATS 0 #define configUSE_TRACE_FACILITY 0 #define configUSE_STATS_FORMATTING_FUNCTIONS 0 /* Co-routine related definitions. */ #define configUSE_CO_ROUTINES 0 #define configMAX_CO_ROUTINE_PRIORITIES 1 /* Software timer related definitions. */ #define configUSE_TIMERS 1 #define configTIMER_TASK_PRIORITY 3 #define configTIMER_QUEUE_LENGTH 10 #define configTIMER_TASK_STACK_DEPTH configMINIMAL_STACK_SIZE /* Interrupt nesting behaviour configuration. */ #define configKERNEL_INTERRUPT_PRIORITY [dependent of processor] #define configMAX_SYSCALL_INTERRUPT_PRIORITY [dependent on processor and application] #define configMAX_API_CALL_INTERRUPT_PRIORITY [dependent on processor and application] /* Define to trap errors during development. */ #define configASSERT( ( x ) ) if( ( x ) == 0 ) vAssertCalled( __FILE__, __LINE__ ) /* FreeRTOS MPU specific definitions. */ #define configINCLUDE_APPLICATION_DEFINED_PRIVILEGED_FUNCTIONS 0 /* Optional functions - most linkers will remove unused functions anyway. */ #define INCLUDE_vTaskPrioritySet 1 #define INCLUDE_uxTaskPriorityGet 1 #define INCLUDE_vTaskDelete 1 #define INCLUDE_vTaskSuspend 1 #define INCLUDE_xResumeFromISR 1 #define INCLUDE_vTaskDelayUntil 1 #define INCLUDE_vTaskDelay 1 #define INCLUDE_xTaskGetSchedulerState 1 #define INCLUDE_xTaskGetCurrentTaskHandle 1 #define INCLUDE_uxTaskGetStackHighWaterMark 0 #define INCLUDE_xTaskGetIdleTaskHandle 0 #define INCLUDE_xTimerGetTimerDaemonTaskHandle 0 #define INCLUDE_pcTaskGetTaskName 0 #define INCLUDE_eTaskGetState 0 /* A header file that defines trace macro can be included here. */ #endif /* FREERTOS_CONFIG_H */