Why RTOS over bare-metal in FreeRTOS - Visual Breakdown

Concept Flow - Why RTOS over bare-metal

Start Program

↓

Choose bare-metal?

Yes→Single task runs

↓

No task switching

↓

Choose RTOS?

Yes→Multiple tasks run

↓

Tasks switch by scheduler

↓

Program ends

This flow shows the choice between bare-metal and RTOS: bare-metal runs one task at a time with no switching, RTOS runs multiple tasks with scheduler switching.

Execution Sample

FreeRTOS

void main() {
  while(1) {
    task1();
    task2();
  }
}

// RTOS runs tasks concurrently with scheduler

This code shows a bare-metal loop running tasks one after another; RTOS allows tasks to run concurrently with switching.

Execution Table

Step	Task Running	Scheduler Action	Output/Effect
1	task1	No scheduler (bare-metal)	task1 runs fully
2	task2	No scheduler (bare-metal)	task2 runs fully
3	task1	No scheduler (bare-metal)	task1 runs again
4	task1	Scheduler switches to task2 (RTOS)	task1 runs part, then switches
5	task2	Scheduler switches to task1 (RTOS)	task2 runs part, then switches
6	task1	Scheduler switches to task2 (RTOS)	task1 runs part again

💡 Bare-metal runs tasks sequentially with no switching; RTOS switches tasks to run concurrently.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 4	After Step 5	Final
Current Task	None	task1	task2	task1 (partial)	task2 (partial)	task1/task2 switching
Scheduler Active	No	No	No	Yes	Yes	Yes

Key Moments - 3 Insights

Why does bare-metal run tasks one after another without switching?

Because there is no scheduler to switch tasks, as shown in execution_table rows 1-3 where tasks run fully one by one.

How does RTOS allow multiple tasks to run seemingly at the same time?

RTOS uses a scheduler to switch tasks frequently, shown in execution_table rows 4-6 where tasks run partially and switch.

What happens if a task blocks or waits in bare-metal?

The whole program waits because no other task runs, unlike RTOS where scheduler can switch to other tasks.

Visual Quiz - 3 Questions

Look at the execution_table, what task is running at step 2?

A task1

B task2

C No task

D Scheduler

💡 Hint

Check the 'Task Running' column at step 2 in execution_table.

At which step does the scheduler start switching tasks?

A Step 4

B Step 3

C Step 1

D Step 7

💡 Hint

Look for 'Scheduler switches' in the 'Scheduler Action' column in execution_table.

If we remove the scheduler, how would the 'Current Task' variable change after step 5?

A It would stay on task2 only

B It would keep switching tasks

C It would stay on task1 only

D It would stop running tasks

💡 Hint

Refer to variable_tracker 'Scheduler Active' and 'Current Task' values and execution_table rows 1-3.

Concept Snapshot

Bare-metal runs one task fully before next.
No task switching or scheduler.
RTOS uses scheduler to switch tasks.
Allows multitasking and better responsiveness.
RTOS handles blocking tasks without stopping all.
Choose RTOS for complex, multitask needs.

Full Transcript

This visual trace compares bare-metal and RTOS task running. Bare-metal runs tasks one after another without switching, shown in steps 1-3. RTOS uses a scheduler to switch tasks frequently, allowing multitasking, shown in steps 4-6. Variables track current task and scheduler status. Key moments clarify why bare-metal lacks switching and how RTOS multitasks. Quiz questions check understanding of task running and scheduler action. Summary: bare-metal is simple sequential running; RTOS enables multitasking with scheduler.