AVR Development Arduino Method (Part 7) Embedded Operating System FreeRTOS

FreeRTOS can provide functions such as task management, queue management, interrupt management, resource management and memory management. Because it takes up less resources, it can run on the Arduino UNO R3 development board.

You can download it from https://github.com/greiman/FreeRTOS-Arduino , unzip the FreeRTOS-Arduino-master.zip, and copy all the contents in the /FreeRTOS-Arduino-master/libraries folder to the libraries folder under the Arduino IDE installation directory. Here is the frBlink example it provides:

 1 // frBlink.ino

 2 #include AVR.h>

 3 

 4 const uint8_t LED_PIN = 13;

 5 SemaphoreHandle_t sem;

 6 

 7 static void Thread1(void* arg) {

 8   while (1) {

 9     xSemaphoreTake(sem, portMAX_DELAY);

10     digitalWrite(LED_PIN, LOW);

11   }

12 }

13 

14 static void Thread2(void* arg) {

15   pinMode(LED_PIN, OUTPUT);

16 

17   while (1) {

18     digitalWrite(LED_PIN, HIGH);

19     vTaskDelay((200L * configTICK_RATE_HZ) / 1000L);

20     xSemaphoreGive(sem);

21     vTaskDelay((200L * configTICK_RATE_HZ) / 1000L);

22   }

23 }

24 

25 void setup() {

26   portBASE_TYPE s1, s2;

27 

28   Serial.begin(9600);

29   

30   sem = xSemaphoreCreateCounting(1, 0);

31   s1 = xTaskCreate(Thread1, NULL, configMINIMAL_STACK_SIZE, NULL, 2, NULL);

32   s2 = xTaskCreate(Thread2, NULL, configMINIMAL_STACK_SIZE, NULL, 1, NULL);

33   if (sem== NULL || s1 != pdPASS || s2 != pdPASS ) {

34     Serial.println(F("Creation problem"));

35     while(1);

36   }

37 

38 vTaskStartScheduler();

39   Serial.println(F("Insufficient RAM"));

40   while(1);

41 }

42 

43 void loop() {

44 }

This example has the same effect as the Blink example, which demonstrates FreeRTOS's task creation, semaphores, and task sleep functions.

In addition to the 6 basic examples, an additional 16 examples are provided in the FreeRTOSBook folder; due to space constraints, please refer to these 22 examples or other books about FreeRTOS.