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Real devices do many things at once: blink a light while watching a button. With non-blocking timing your board can finally juggle both.

The trick is one timer per task. Give the blink its own previousMillis and interval, separate from anything else you want to run.

Keep a dedicated previousMillis for the LED so its schedule never tangles with other timed jobs in the same loop.

First, the blink block checks its own timer. When 500 milliseconds pass it toggles the LED and resets, then control moves on.

Right after the blink block, you read the button on every single pass. Because nothing froze, no press is ever missed.

Now the same loop handles both: it times the blink and checks the button thousands of times a second. They feel simultaneous.

Want more? Just add another timer and block, like reading a sensor every two seconds. The pattern scales to many tasks cleanly.

The rule that makes it work: never block. Keep every part of the loop quick so it can return often and serve all tasks fairly.

The board still does one thing at a time, just very fast. This is cooperative multitasking, where each task does a little and yields.

One long delay anywhere breaks the whole illusion, since it freezes every task. Replace pauses with millis checks to keep things smooth.

This state machine style, many small timed checks in one loop, is how responsive sensors, displays, and connected devices are really built.

How does one loop blink an LED and read a button at the same time?

You combined timers in one loop to multitask: blink and read a button together, with no blocking delay. That is the core skill behind real IoT devices. 🚀