Porting STM32-FreeRTOS and Simulation in Proteus

Introduction to FreeRTOS

FreeRTOS is an open-source real-time operating system (RTOS) designed for embedded systems. It provides the following core features:

1. Task Management: Supports concurrent execution of multiple tasks, with the ability to set task priorities.

2. Memory Management: Provides dynamic memory allocation mechanisms (such as heap_1, heap_2, heap_4, etc.).

3. Inter-task Communication: Supports mechanisms such as queues, semaphores, and mutexes.

4. Timers: Provides software timer functionality.

5. Interrupt Management: Supports communication between interrupt service routines (ISRs) and tasks.

6. Portability: The code of FreeRTOS is highly modular, making it easy to port to different hardware platforms.

FreeRTOS is widely used in resource-constrained embedded devices, such as sensor nodes, industrial controllers, consumer electronics, and automotive electronics.

Detailed Steps to Port FreeRTOS in STM32 Using Standard Libraries

1. Preparation

• Hardware: STM32F103C8.

• Software:

• Keil MDK.

• STM32 Standard Peripheral Library (StdPeriph Library).

• FreeRTOS Source Code: Download the latest version from the FreeRTOS official website.

2. Porting Steps

2.1 Create Project

1. Create a new STM32 project in Keil using the standard peripheral library template.

2.2 Add FreeRTOS Source Code

1. Copy the FreeRTOS source code into the project directory, typically including the following files:

• <span>FreeRTOS/Source/*</span>: FreeRTOS core source code.

• <span>FreeRTOS/Source/portable/[compiler]/[architecture]</span>: Port layer files (e.g., <span>RVDS/ARM_CM3</span> for Cortex-M3).

• <span>FreeRTOS/Source/include/*</span>: FreeRTOS header files.

Add the following files to the project:

• <span>tasks.c</span>, <span>queue.c</span>, <span>list.c</span>, <span>timers.c</span>: FreeRTOS core files.

• <span>port.c</span>: Port layer file.

• <span>heap_4.c</span>: Memory management implementation (recommended to use heap_4).

2.3 Configure FreeRTOS

1. Modify the <span>FreeRTOSConfig.h</span> file to configure FreeRTOS parameters:

#define configUSE_PREEMPTION 1

#define configUSE_TIME_SLICING 1

#define configUSE_PORT_OPTIMISED_TASK_SELECTION 1

#define configUSE_TICKLESS_IDLE 0

#define configCPU_CLOCK_HZ (SystemCoreClock)

#define configTICK_RATE_HZ ((TickType_t)1000)

#define configMAX_PRIORITIES (32)

#define configMINIMAL_STACK_SIZE ((unsigned short)128)

#define configMAX_TASK_NAME_LEN (16)

#define configUSE_16_BIT_TICKS 0

#define configIDLE_SHOULD_YIELD 1

#define configUSE_QUEUE_SETS 0

#define configUSE_TASK_NOTIFICATIONS 1

#define configUSE_MUTEXES 0

#define configUSE_RECURSIVE_MUTEXES 0

#define configUSE_COUNTING_SEMAPHORES 0

#define configQUEUE_REGISTRY_SIZE 10

#define configUSE_APPLICATION_TASK_TAG 0

#define configSUPPORT_DYNAMIC_ALLOCATION 1

#define configSUPPORT_STATIC_ALLOCATION 0

#define configTOTAL_HEAP_SIZE ((size_t)(10*1024))

Implement the SysTick interrupt in <span>stm32f10x_it.c</span>:

void SysTick_Handler(void)

{

if(xTaskGetSchedulerState()!=taskSCHEDULER_NOT_STARTED)

{

xPortSysTickHandler();

}

}

2.4 Write Task Code

Create tasks in <span>main.c</span>:

int main()

{

SysTick_Init(72);

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4);

GPIO_LCD_Init();

GPIO_FillScreen(BLUE);

// Create start task

xTaskCreate((TaskFunction_t)start_task,

(const char*)