Short answer: Yes—sometimes. “Arduino” (the IDE + sketches) doesn’t include an RTOS by default, but many Arduino-compatible boards either ship with one or can use one easily.

**Native Arduino "OS" - The Reality**
Default [Arduino](https://www.ampheo.com/c/development-board-arduino) doesn't have a true RTOS. It runs:

* Simple superloop architecture (setup() + loop())
* Cooperative multitasking (you manually manage task switching)
* Interrupt-driven for time-critical events
* No preemption, no task priorities, no memory protection

cpp

// Default Arduino structure - NO RTOS
void setup() {
  // Initialization
}

void loop() {
  // Your main code runs sequentially
  task1();
  task2(); 
  task3();
  // You must manually manage timing and task switching
}

**Popular RTOS Options for Arduino**
**1. FreeRTOS - Most Popular Choice**
**Supported Boards:**

* [Arduino Due](https://www.ampheo.com/product/a000062-25542566), Zero, MKR series (ARM Cortex-M)
* ESP32, ESP8266 (built-in FreeRTOS)
* [SAMD21](https://www.onzuu.com/search/SAMD21)/[SAMD51](https://www.ampheo.com/search/SAMD51) boards

**Installation:**

cpp

// Arduino IDE: Sketch → Include Library → Manage Libraries
// Search for "FreeRTOS" by Richard Barry

// PlatformIO: Add to platformio.ini
lib_deps = freertos
Basic Example:

cpp
#include <Arduino_FreeRTOS.h>
#include <task.h>

// Task function prototypes
void TaskBlink(void *pvParameters);
void TaskAnalogRead(void *pvParameters);

void setup() {
  Serial.begin(9600);
  
  // Create tasks
  xTaskCreate(TaskBlink, "Blink", 128, NULL, 1, NULL);
  xTaskCreate(TaskAnalogRead, "AnalogRead", 128, NULL, 1, NULL);
  
  // Start scheduler - NEVER RETURNS!
  vTaskStartScheduler();
}

void loop() {
  // Empty - scheduler takes over
}

void TaskBlink(void *pvParameters) {
  pinMode(LED_BUILTIN, OUTPUT);
  while(1) {
    digitalWrite(LED_BUILTIN, HIGH);
    vTaskDelay(1000 / portTICK_PERIOD_MS); // Non-blocking delay
    digitalWrite(LED_BUILTIN, LOW);
    vTaskDelay(1000 / portTICK_PERIOD_MS);
  }
}

void TaskAnalogRead(void *pvParameters) {
  while(1) {
    int sensorValue = analogRead(A0);
    Serial.println(sensorValue);
    vTaskDelay(100 / portTICK_PERIOD_MS);
  }
}

**2. ChibiOS - High Performance**
Best for: SAM-based boards (Due, Zero)
Features: Hard real-time capabilities, lower latency

**3. mbed OS (for ARM boards)**
* [Arduino Nano 33 BLE](https://www.ampheo.com/product/abx00030-25542527), [Portenta H7](https://www.ampheo.com/product/abx00042-25542693), [Nicla Vision](https://www.ampheo.com/product/abx00051-25542502)
* Full-featured RTOS with networking, security

**4. ESP32's Built-in FreeRTOS**

cpp

// ESP32 has FreeRTOS built-in - no library needed
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>

void anotherTask(void *parameter) {
  while(1) {
    Serial.println("This is another task");
    vTaskDelay(1000 / portTICK_PERIOD_MS);
  }
}

void setup() {
  Serial.begin(115200);
  xTaskCreate(anotherTask, "another Task", 10000, NULL, 1, NULL);
}

void loop() {
  Serial.println("This is Arduino loop");
  delay(1000);
}

**RTOS Benefits for Arduino Projects**
**Concurrent Task Management**

cpp

// Without RTOS - manual cooperative multitasking
unsigned long previousMillis1 = 0;
unsigned long previousMillis2 = 0;

void loop() {
  unsigned long currentMillis = millis();
  
  // Task 1 every 1000ms
  if (currentMillis - previousMillis1 >= 1000) {
    previousMillis1 = currentMillis;
    task1();
  }
  
  // Task 2 every 500ms  
  if (currentMillis - previousMillis2 >= 500) {
    previousMillis2 = currentMillis;
    task2();
  }
}

// With RTOS - automatic preemptive scheduling
xTaskCreate(task1, "Task1", 1000, NULL, 1, NULL);
xTaskCreate(task2, "Task2", 1000, NULL, 2, NULL); // Higher priority

**RTOS Features Available:**

**When to Use RTOS on Arduino**
**Use RTOS when you need:**
1. Multiple time-critical tasks running simultaneously
2. Complex timing requirements
3. Responsive systems that can't be blocked by long operations
4. Network stack + application logic concurrently
5. Professional embedded development practices

**Stick with default loop() when:**
* Simple projects with 1-2 tasks
* Basic [sensor](https://www.ampheo.com/c/sensors) reading + LED control
* Beginners learning Arduino basics
* Memory-constrained devices (Uno, Nano)

**Practical Implementation Examples**
**Example 1: Data Logger with RTOS**

cpp

#include <Arduino_FreeRTOS.h>
#include <semphr.h>

SemaphoreHandle_t xSerialSemaphore;

void TaskSensorRead(void *pvParameters) {
  while(1) {
    // Read sensor
    int value = analogRead(A0);
    
    // Safely print with semaphore
    if (xSemaphoreTake(xSerialSemaphore, portMAX_DELAY) == pdTRUE) {
      Serial.print("Sensor: ");
      Serial.println(value);
      xSemaphoreGive(xSerialSemaphore);
    }
    vTaskDelay(100 / portTICK_PERIOD_MS);
  }
}

void TaskDataSave(void *pvParameters) {
  while(1) {
    // Save data to SD card
    vTaskDelay(1000 / portTICK_PERIOD_MS);
  }
}

void setup() {
  Serial.begin(9600);
  xSerialSemaphore = xSemaphoreCreateMutex();
  
  xTaskCreate(TaskSensorRead, "Sensor", 256, NULL, 2, NULL);
  xTaskCreate(TaskDataSave, "Save", 256, NULL, 1, NULL);
  
  vTaskStartScheduler();
}

**Example 2: Robot Controller**

cpp

// Separate tasks for different robot functions
xTaskCreate(TaskMotorControl, "Motors", 512, NULL, 3, NULL);     // High priority
xTaskCreate(TaskSensorFusion, "Sensors", 1024, NULL, 2, NULL);   // Medium priority  
xTaskCreate(TaskCommunication, "Comm", 512, NULL, 1, NULL);      // Low priority

**Board Compatibility Guide**

**Getting Started Tutorial**
**Step 1: Install FreeRTOS Library**
1. Arduino IDE → Tools → Manage Libraries
2. Search for "FreeRTOS by Richard Barry"
3. Click Install

**Step 2: Basic Task Creation**

cpp

#include <Arduino_FreeRTOS.h>

void setup() {
  xTaskCreate(MyTask, "MyTask", 128, NULL, 1, NULL);
  vTaskStartScheduler();
}

void MyTask(void *pvParameters) {
  pinMode(LED_BUILTIN, OUTPUT);
  while(1) {
    digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
    vTaskDelay(500 / portTICK_PERIOD_MS);
  }
}

void loop() {} // Unused

**Step 3: Monitor Task Status**

cpp

// Add to setup() before scheduler starts
Serial.begin(115200);
configUSE_TRACE_FACILITY = 1; // Enable task stats

// Check task states periodically
void TaskMonitor(void *pvParameters) {
  while(1) {
    Serial.printf("Free heap: %d\n", xPortGetFreeHeapSize());
    vTaskDelay(5000 / portTICK_PERIOD_MS);
  }
}

**Conclusion**
Yes, [Arduino](https://www.ampheoelec.de/c/development-board-arduino) can run RTOS, but you need to:

1. Choose compatible hardware (ESP32, ARM-based boards recommended)
2. Install appropriate RTOS library (FreeRTOS most common)
3. Understand RTOS concepts (tasks, semaphores, queues)
4. Manage limited resources on smaller boards

For new projects where RTOS functionality is needed, ESP32 is highly recommended due to its built-in FreeRTOS support and ample resources.