2 · Inputs & sensors
Threshold with hysteresis
Advanced20 min
Goal
Stop the output from flickering when the reading hovers around the threshold.
Why it matters
Two thresholds (high and low) stabilise any real control loop: thermostat, night light, alarm.
What you need
- Arduino UNO board
- 5 mm LED
- 220 Ω resistor
Nothing to buy: every component below is simulated in the browser.
Steps
- 01Define LOW_THRESHOLD and HIGH_THRESHOLD (e.g. 380 and 420).
- 02Switch on only below LOW_THRESHOLD, off only above HIGH_THRESHOLD.
- 03Remember the current state between loop iterations.
This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.
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 20 minutes, advanced level, in 3 guided steps.
- What should I know before starting?
- The previous tutorial in the series, “Light sensor (LDR)”, 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.
For teachers
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