گروه فنی مهندسی آرکام

با فراخوانی تابع vTaskStartScheduler() در تابع main کنترل روند اجرای برنامه را به FreeRTOS می سپاریم.. خب! برنامه باید در حالت non-RTOS نیز عملکرد صحیحی داشته باشد... از این امر باید مطمئن شوید...

سیستم عامل ↔ زمانبندی

خب! برای زمانبدی به یک تایمر احتیاج داریم...

EVERY RTOS PORT USES A TIMER TO GENERATE A PERIODIC TICK INTERRUPT. MANY PORTS USE ADDITIONAL INTERRUPTS TO MANAGE CONTEXT SWITCHING...

FreeRTOS - Basic directory structure

The core RTOS code is contained in three files, which are called tasks.c, queue.c and list.c. These three files are in the FreeRTOS/Source directory. The same directory contains two optional files called timers.c and croutine.c which implement software timer and co-routine functionality respectively.

Core FreeRTOS Source Code (FreeRTOSV8.1.2/FreeRTOS/Source)

FreeRTOS/Source/tasks.c

FreeRTOS/Source/queue.c

FreeRTOS/Source/list.c.

FreeRTOS/Source/timers.c

FreeRTOS/Source/croutine.c

Each supported processor architecture requires a small amount of architecture specific RTOS code. This is the RTOS portable layer, and it is located in the FreeRTOS/Source/Portable/[compiler]/[architecture] subdirectories, where [compiler] and [architecture] are the compiler used to create the port, and the architecture on which the port runs, respectively.             

RTOS Portable Layer (FreeRTOSV8.1.2/FreeRTOS/Source/portable/RVDS)

FreeRTOS/Source/portable/YOUR_PORT/port.c

Anatomy of a minimum FreeRTOS Project

Source Files

FreeRTOS/Source/tasks.c

FreeRTOS/Source/queue.c

FreeRTOS/Source/list.c

FreeRTOS/Source/portable/[compiler]/[architecture]/port.c

FreeRTOS/Source/portable/MemMang/heap_x.c // where 'x' is 1, 2, 3 or 4.

- If the directory that contains the port.c file also contains an assembly language file, then the assembly language file must also be used...

- If you need software timer functionality, then include FreeRTOS/Source/timers.c...

- If you need co-routine functionality, then include FreeRTOS/Source/croutine.c

Header Files

FreeRTOS/Source/include

FreeRTOS/Source/portable/[compiler]/[architecture]

Configuration File

Src/FreeRTOSConfig.h

configTOTAL_HEAP_SIZE      // total amount of available heap space

configMINIMAL_STACK_SIZE   // size of the stack used by the idle task

- It is advised to copy the settings from an official FreeRTOS demo provided for the same microcontroller architecture

Memory Management

The RTOS kernel allocates RAM each time a task, queue, mutex, software timer, semaphore or event group is created...

The standard C library malloc() and free() functions can sometimes be used for this purpose, but they are not safe, deterministic...

One embedded / real time system can have very different RAM and timing requirements to another - so a single RAM allocation algorithm will only ever be appropriate for a subset of applications...

Creating a New FreeRTOS Project

0- Import FreeRTOS folder to our project tree

1- Link following sources to your project

FreeRTOS/Source/list.c

FreeRTOS/Source/queue.c

FreeRTOS/Source/tasks.c

FreeRTOS/Source/portable/MemMang/heap_YOUR_HEAP.c

FreeRTOS/Source/portable/YOUR_PORT/port.c

FreeRTOS/Source/portable/YOUR_PORT/portASM.s

2- Copy FreeRTOSConfig.h from closest demo example to your include path

3- Add following directories to you include path

FreeRTOS\Source\include

4- You may need to change Startup.S to the one from closest demo example, if threads are not starting

5- Modify your main.c ...!!!