Press once for on, once for off
The difference between a level and an edge, a variable that remembers, and the debounce window that makes a mechanical switch usable.
Open it in the simulatorAll paths
Interactive devices on the Uno
Read people and sensors without blocking, control an output, then finish with two playable builds.
0 of 9 done
What you will build
4 projects, built step by step
9 lessons in 4 chapters, about 8 hours on a simulated Arduino Uno R3. Free, in your browser, every step checked by the simulator.
Blinking and listening at the same time
The payoff for non-blocking code: a board that keeps a rhythm and still answers a button in microseconds. Feel the difference by breaking it.
Open it in the simulatorBrightness from a digital pin
Eight duty cycles on pin 9 next to a pin that can only be on or off. What PWM is, which pins have it, and what it is not good for.
Open it in the simulatorProject: a metronome
A click on a piezo, a lamp on the beat, and two buttons that change the tempo without missing one. Making a note out of a pin.
Open it in the simulatorThe map
Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
Read intent
Wire a button correctly and turn a changing level into one deliberate action.
- Open160 XP
Reading a pin, and the pull-up
A button with no resistor of its own, an input that must never float, and why pressed reads low. The single most common wiring in embedded work.
0 of 6 steps
- ProjectLocked320 XP
Press once for on, once for off
The difference between a level and an edge, a variable that remembers, and the debounce window that makes a mechanical switch usable.
0 of 6 steps
Chapter 2
Stay responsive
Measure elapsed time so one job never makes the board deaf to another.
- Locked160 XP
Two rates at once, without delay
The pattern that unlocks everything else: keep when each thing last happened, and ask the time instead of waiting for it.
0 of 6 steps
- ProjectLocked320 XP
Blinking and listening at the same time
The payoff for non-blocking code: a board that keeps a rhythm and still answers a button in microseconds. Feel the difference by breaking it.
0 of 6 steps
Chapter 3
Sense and act
Turn a changing voltage into a stable decision and a proportional output.
- Locked160 XP
Reading a voltage
The ADC turns a voltage into a number from 0 to 1023. Build a divider, read two taps of it, and work out what a count is worth.
0 of 6 steps
- Locked160 XP
Deciding from a reading
A lamp that fades up when the sensor says dark, and an indicator that does not. What a threshold is, why a ramp looks better than a jump, and where hysteresis comes in.
0 of 6 steps
- ProjectLocked320 XP
Brightness from a digital pin
Eight duty cycles on pin 9 next to a pin that can only be on or off. What PWM is, which pins have it, and what it is not good for.
0 of 6 steps
Chapter 4
Finished builds
Use inputs, timing and feedback together in two projects you can play.
- Locked160 XP
Project: a reaction timer
A lamp at a random moment, a button, and the milliseconds in between. Randomness, measuring time, and catching a cheat.
0 of 6 steps
- ProjectLocked320 XP
Project: a metronome
A click on a piezo, a lamp on the beat, and two buttons that change the tempo without missing one. Making a note out of a pin.
0 of 6 steps
Syllabus
Every lesson in the course
All 9 lessons, in order, each with what it covers. Any of them opens in the editor right away.
Read intent
- Reading a pin, and the pull-upA button with no resistor of its own, an input that must never float, and why pressed reads low. The single most common wiring in embedded work.
- Press once for on, once for offThe difference between a level and an edge, a variable that remembers, and the debounce window that makes a mechanical switch usable.
Stay responsive
- Two rates at once, without delayThe pattern that unlocks everything else: keep when each thing last happened, and ask the time instead of waiting for it.
- Blinking and listening at the same timeThe payoff for non-blocking code: a board that keeps a rhythm and still answers a button in microseconds. Feel the difference by breaking it.
Sense and act
- Reading a voltageThe ADC turns a voltage into a number from 0 to 1023. Build a divider, read two taps of it, and work out what a count is worth.
- Deciding from a readingA lamp that fades up when the sensor says dark, and an indicator that does not. What a threshold is, why a ramp looks better than a jump, and where hysteresis comes in.
- Brightness from a digital pinEight duty cycles on pin 9 next to a pin that can only be on or off. What PWM is, which pins have it, and what it is not good for.
Finished builds
- Project: a reaction timerA lamp at a random moment, a button, and the milliseconds in between. Randomness, measuring time, and catching a cheat.
- Project: a metronomeA click on a piezo, a lamp on the beat, and two buttons that change the tempo without missing one. Making a note out of a pin.
Keep going
The next course on your track
Interactive devices on the Uno is part of the embedded track, a ladder of courses from zero to expert.
Talk to chips: I2C, SPI and UART
The three buses every sensor, screen and radio speaks, on the Uno: serial between two boards, I2C scans and shared buses, SPI screens and an SD card, the logic analyzer, and a weather station that uses them all.
Open the next courseEmbedded track
Arduino, ESP32, Raspberry Pi Pico and STM32: pins, timing, buses, motors, WiFi, registers and debugging, every lesson checked on a simulated board.
See every course on the trackKits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Find your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
See every kitQuestions
About Interactive devices on the Uno
Is Interactive devices on the Uno free?
Yes. All 9 lessons of Interactive devices on the Uno are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need a real Arduino Uno R3?
No. Every lesson runs on a simulated Arduino Uno R3 with its parts on the canvas, and the simulator checks each step as you go. When you want to build it for real, the same wiring and code work on a real board.
How long does Interactive devices on the Uno take?
About 8 hours: 9 lessons in 4 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: Press once for on, once for off, Blinking and listening at the same time, Brightness from a digital pin and Project: a metronome.
Where do I start?
With "Reading a pin, and the pull-up", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.