STM32F103 FreeRtos migration notes

RTOS version: FreeRTOS_V8.2.2

1. Download the FreeRTOS source file.
       You can download it from Baidu, or download it from the official website http://www.freertos.org/a00104.html.
       You can download it from the following location

       The latest version is 8.2.2
. Download the source code, unzip it, and add the source code to the project.
      2.1 Create a new transplant project (you can also copy Atom's), and create a folder FreeRTOS in the project to store the source code.
      2.2 Open the unzipped source code "..\FreeRTOSv8.2.2", which contains several folders and files.

The red circle in the picture above is the source code. Copy the entire folder to the "FreeRTOS" folder of the new project.
2.4 In the source code folder "..\FreeRTOSv8.2.2\FreeRTOS\Demo\CORTEX_STM32F103_Keil", find the file "FreeRTOSConfig.h" and copy it to the project folder "FreeRTOS"

3. Open the MDK software, create a new project, and add files

Add files as shown above. The red box is the FreeRTOS file added;
"port.c" file path..\FreeRTOS\Source\portable\RVDS\ARM_CM3
"heap_2.c" file path..\FreeRTOS\Source\portable\MemMang
"list.c", "queue.c", "tasks.c" file path..\FreeRTOS\Source

5. After completing the above work, write the main function

#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "misc.h"
#include "led.h"

void LED0_Task(void *pvParameters);
void LED1_Task(void *pvParameters);

int main()
{     
   LED_Init(); //Initialize the hardware interface connected to the LED
   xTaskCreate(LED0_Task,(const char *)"LED0",configMINIMAL_STACK_SIZE,NULL,tskIDLE_PRIORITY+3,NULL);
   xTaskCreate(LED1_Task,(const char *)"LED1",configMINIMAL_STACK_SIZE,NULL,tskIDLE_PRIORITY+4,NULL);
   vTaskStartScheduler();
}

void LED0_Task(void *pvParameters)
{
   while(1)
   {
       LED0=!LED0;
       vTaskDelay(1000/portTICK_RATE_MS);
   }
}

void LED1_Task(void *pvParameters)
{
   while(1)
   {
       LED1=!LED1;
       vTaskDelay(300/portTICK_RATE_MS);
   }
}

Only two LEDs are set up, flashing at different frequencies

6. To modify the startup file, first remove the read-only attribute of the startup file, otherwise it cannot be modified (the ones that have been removed are skipped)

I don't understand why this was changed. IMPORT and EXPORT are used to call internal reference files and external reference files respectively, which is similar to the meaning of extern in C language. Modify these places to make the function name the same as that in the port.c file, so that the freertos function can be called.

7. After finishing, I started compiling and correcting the errors. After completion, I downloaded it and saw that the two lights were flashing at different frequencies.

8. The above is almost complete. In addition, what should we do when an interrupt occurs? A protection mechanism is needed.

//External interrupt 2 service routine
void EXTI2_IRQHandler(void)
{
   taskENTER_CRITICAL();

   delay_us(1000);
   if(KEY2==0) //Key KEY2
   {
       BEEP=!BEEP;
   }    
   
   EXTI_ClearITPendingBit(EXTI_Line2); //Clear the interrupt flag on LINE2  
   taskEXIT_CRITICAL();
}

After testing, I found that based on the two lights, I wrote a KEY (using interrupt mode) to trigger the buzzer, which is also feasible.

I have understood the above, which is basically an introduction. Now I will mainly study UCOS-III. Although freertos is completely free and UCOS needs to be charged, most domestic companies still use UCOS as long as they do not export. It is better to follow the crowd to make a living. The way of thinking is similar.

I have summarized three stages of MCU time utilization for engineers.

In the first stage, as long as there is a delay, use the delay method and wait until you get hurt.

The second stage is to use the flag bit. I have always done this before. If I want to detect something in 10ms, I will set a main timer and constantly check whether it has been detected. If it has been detected, I will execute it. If it has not been detected, I will execute other things.

In the third stage, the operating system is used to save the time for the above queries. When a task is completed, it will automatically enter the next high-priority place. Although there is an idle mode, the efficiency is still very high when tasks are concentrated.