Reducing power consumption tips in Arduino - Time & Space Complexity

Time Complexity: Reducing power consumption tips

O(n)

Understanding Time Complexity

When we write code to save power on an Arduino, we want to know how much work the code does as it runs.

We ask: how does the time the code takes change when we add more steps or checks?

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

void loop() {
  delay(1000); // wait 1 second
  digitalWrite(LED_BUILTIN, HIGH); // turn LED on
  delay(100); // short on time
  digitalWrite(LED_BUILTIN, LOW); // turn LED off
  delay(1000); // wait 1 second
}
    

This code blinks an LED with delays to save power by turning the LED off most of the time.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The loop function repeats forever.
• How many times: Each loop cycle runs once, but inside it, delay pauses the program.

How Execution Grows With Input

Explain the growth pattern intuitively.

Input Size (n)	Approx. Operations
10	10 cycles of loop, each with fixed delays
100	100 cycles, same fixed delays each time
1000	1000 cycles, delays do not change

Pattern observation: The time spent grows linearly with the number of cycles, but each cycle takes the same fixed time.

Final Time Complexity

Time Complexity: O(n)

This means the total time grows directly with how many times the loop runs, but each loop takes a fixed amount of time.

Common Mistake

[X] Wrong: "Adding more delay calls makes the program faster."

[OK] Correct: Delay pauses the program, so more delays actually make it slower, not faster.

Interview Connect

Understanding how your code's timing grows helps you write better programs that save power and run efficiently on small devices like Arduino.

Self-Check

"What if we replaced delay() with a non-blocking timer? How would the time complexity change?"