Do I need to buy hardware for this tutorial?

No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.

Which components are used?

Arduino UNO board, 5 mm LED, 220 Ω resistor. They are already available in the simulator library.

How long does it take?

About 22 minutes, expert level, in 3 guided steps.

What should I know before starting?

The previous tutorial in the series, “Three tasks in parallel”, is enough preparation. No software install is required.

Is the code provided and checked?

The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

All tutorials

5 · Communication & data

Detect a freeze (watchdog)

Expert22 min

Goal

Report when a reading has not been refreshed for 3 seconds.

Why it matters

A reliable system detects its own failures instead of showing stale data.

What you need

Arduino UNO board
5 mm LED
220 Ω resistor

Nothing to buy: every component below is simulated in the browser.

Steps

01Store the timestamp of the last valid reading.
02In loop(), compare millis() to that timestamp.
03Past 3000 ms, light the alert LED and report on the serial port.

This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.

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Frequently asked questions

Do I need to buy hardware for this tutorial?: No. Everything runs in the browser: Circuitly simulates the board, the components and the code. Real hardware is optional if you want to rebuild the circuit afterwards.
Which components are used?: Arduino UNO board, 5 mm LED, 220 Ω resistor. They are already available in the simulator library.
How long does it take?: About 22 minutes, expert level, in 3 guided steps.
What should I know before starting?: The previous tutorial in the series, “Three tasks in parallel”, is enough preparation. No software install is required.
Is the code provided and checked?: The simulator checks your wiring and your code automatically at every step, and shows the commented solution if you get stuck.

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