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Write an Arduino sketch and run it on a 3D board — no hardware needed.

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The course

18 worlds · 264 lessons

World 1 · Foundations

FREEElectricity from absolute zero
  1. 01What is electricity?Electrons, charge and flow · 5 min
  2. 02Voltage, Current, ResistanceThe three core quantities · 7 min
  3. 03Your first circuitBattery → resistor → LED · 7 min
  4. 04Ohm’s Law in practiceV = I × R · 8 min
  5. 05Reading resistor colorsDecode the color bands · 6 min
  6. 06Inside the atomProtons, neutrons and free electrons · 6 min
  7. 07Electric chargePositive, negative and attraction · 5 min
  8. 08Conductors vs insulatorsWhat lets current through · 6 min
  9. 09Current, up closeAmps and the direction of flow · 6 min
  10. 10Voltage, up closeThe pressure that drives current · 6 min
  11. 11Resistance, up closeOpposing the flow · 6 min
  12. 12Rearranging Ohm’s LawSolve for V, I or R · 7 min
  13. 13The closed loopWhy a circuit must complete · 5 min
  14. 14Batteries & cellsWhere the voltage comes from · 6 min
  15. 15Cells in seriesStacking voltage · 6 min
  16. 16The LEDA one-way light · 6 min
  17. 17Current-limiting resistorsProtecting the LED · 7 min
  18. 18The resistor color codeReading every band · 7 min
  19. 19Power & wattsHow fast energy is used · 7 min
  20. 20Energy & your billWatts over time · 6 min
  21. 21Short circuitsWhen current finds a shortcut · 6 min
  22. 22Open circuitsA break in the path · 5 min
  23. 23SwitchesOpening and closing on demand · 5 min
  24. 24Ground & referenceThe zero-volt baseline · 6 min
  25. 25Schematic symbolsThe language of circuits · 6 min
  26. 26Using a multimeterVolts, amps and ohms · 7 min
  27. 27Ammeter vs voltmeterSeries and parallel meters · 6 min
  28. 28AC vs DCTwo kinds of current · 6 min
  29. 29FrequencyCounting the cycles · 6 min
  30. 30Static electricityCharge at rest · 5 min
  31. 31ElectromagnetismCurrent makes magnetism · 6 min
  32. 32A taste of parallelMore than one path · 6 min

World 2 · Circuits

PROBuild and combine components
  1. 01Series vs ParallelTwo ways to wire components · 6 minPRO
  2. 02The breadboardPrototype without soldering · 5 minPRO
  3. 03Switches & buttonsControlling the flow · 5 minPRO
  4. 04The voltage dividerMake any voltage you need · 6 minPRO
  5. 05Series circuits in depthOne path, shared current · 6 minPRO
  6. 06Parallel circuits in depthMany paths, shared voltage · 7 minPRO
  7. 07Choosing series or parallelWhen to use which · 6 minPRO
  8. 08Building on a breadboardFrom schematic to board · 6 minPRO
  9. 09Momentary vs latchingTwo kinds of switch · 5 minPRO
  10. 10Pull-up resistorsDefaulting an input HIGH · 6 minPRO
  11. 11Pull-down resistorsDefaulting an input LOW · 5 minPRO
  12. 12Voltage divider mathSolving for Vout · 7 minPRO
  13. 13The potentiometerAn adjustable divider · 6 minPRO
  14. 14The LDR (light sensor)Resistance that follows light · 6 minPRO
  15. 15The thermistor (temp sensor)Resistance vs temperature · 6 minPRO
  16. 16CapacitorsStoring charge · 7 minPRO
  17. 17What capacitors are forSmoothing and timing · 6 minPRO
  18. 18The diodeA one-way valve · 6 minPRO
  19. 19The LED as a diodeLight from one-way current · 6 minPRO
  20. 20Rectification introTurning AC into DC · 6 minPRO
  21. 21Transistor as a switchA tiny signal controls a big load · 7 minPRO
  22. 22Transistor as amplifierMaking signals bigger · 7 minPRO
  23. 23The relayAn electrically-driven switch · 6 minPRO
  24. 24Logic gatesAND, OR, NOT · 7 minPRO
  25. 25Combining gatesNAND, NOR and beyond · 6 minPRO
  26. 26RC timingResistor + capacitor delays · 7 minPRO
  27. 27Current limiting in depthSizing the series resistor · 7 minPRO
  28. 28Kirchhoff’s voltage lawVoltages around a loop · 6 minPRO
  29. 29Kirchhoff’s current lawCurrents at a junction · 6 minPRO
  30. 30Measuring a dividerProbe Vout with a meter · 6 minPRO
  31. 31Decoupling capacitorsKeeping the rail clean · 6 minPRO
  32. 32Troubleshooting a dead circuitA debugging checklist · 7 minPRO

World 3 · Arduino 101

PROWrite code that controls hardware
  1. 01Meet Arduino UnoThe board and its pins · 5 minPRO
  2. 02Blink — your first sketchTurn an LED on and off · 8 minPRO
  3. 03Digital output: traffic lightDrive three LEDs in sequence · 10 minPRO
  4. 04Digital input: a buttonReact to the real world · 10 minPRO
  5. 05The Serial MonitorPrint and debug · 8 minPRO
  6. 06The Arduino IDE & sketchWhere code becomes hardware · 6 minPRO
  7. 07Blink speed & timingdelay() controls the beat · 7 minPRO
  8. 08LED_BUILTINThe onboard LED constant · 6 minPRO
  9. 09Two LEDs alternatingBack-and-forth flasher · 8 minPRO
  10. 10Traffic light with helperReuse code with a function · 10 minPRO
  11. 11LED chase (array + for)Light pins one after another · 10 minPRO
  12. 12Knight Rider scannerBounce the light back · 11 minPRO
  13. 13Variables & mathStore and compute values · 8 minPRO
  14. 14if / else decisionsBranch on a condition · 8 minPRO
  15. 15for loopsRepeat a known number of times · 8 minPRO
  16. 16while loopsRepeat until a condition fails · 8 minPRO
  17. 17Writing functionsName a block of code · 9 minPRO
  18. 18Blink without delay (millis)Do many things at once · 11 minPRO
  19. 19Button controls an LEDInput drives output · 9 minPRO
  20. 20Why INPUT_PULLUP?Floating pins & pull resistors · 7 minPRO
  21. 21Toggle on each pressEdge detection basics · 11 minPRO
  22. 22Debouncing a buttonTame the bounce · 8 minPRO
  23. 23Button press counterCount and report · 10 minPRO
  24. 24Two buttons, up & downMultiple inputs · 11 minPRO
  25. 25Serial: print vs printlnSame line or new line · 7 minPRO
  26. 26Serial number basesDEC, HEX & BIN · 8 minPRO
  27. 27Random blinksUnpredictable timing · 8 minPRO
  28. 28Digital vs analog pinsKnow your pin types · 7 minPRO
  29. 29do / while loopsRun at least once · 8 minPRO
  30. 30Capstone: non-blocking traffic lightPut it all together · 12 minPRO

World 4 · Arduino Projects

PROPWM, sensors, servos & more
  1. 01Fading an LED (PWM)analogWrite & duty cycle · 10 minPRO
  2. 02Reading a potentiometeranalogRead & map · 10 minPRO
  3. 03Servo controlMove a motor to an angle · 12 minPRO
  4. 04Buzzer & toneMake some noise · 9 minPRO
  5. 05Automatic night-lightSense light, react · 12 minPRO
  6. 06How PWM really worksDuty cycle & average voltage · 8 minPRO
  7. 07Breathing LEDSmooth fade with sine · 10 minPRO
  8. 08RGB LED colour mixingThree channels, any colour · 11 minPRO
  9. 09RGB rainbow fadeSmoothly cycle the colour wheel · 12 minPRO
  10. 10Mood lampRandom RGB colours · 9 minPRO
  11. 11Inside a servoPulse width = angle · 8 minPRO
  12. 12Servo sweepPan back and forth · 9 minPRO
  13. 13Smooth servo steeringPot → angle, with easing · 11 minPRO
  14. 14Play a melodyNotes & durations in arrays · 12 minPRO
  15. 15Police sirenSweeping tone alarm · 9 minPRO
  16. 16Reaction-time gameButton + LED + millis · 13 minPRO
  17. 17Serial bar meterVisualise a value with text · 10 minPRO
  18. 18How analog sensors workResistance → voltage → number · 8 minPRO
  19. 19Light-level loggerStream readings to Serial · 9 minPRO
  20. 20Light thereminWave your hand, change the pitch · 11 minPRO
  21. 21Reading temperatureTMP36 → degrees Celsius · 11 minPRO
  22. 22ThermostatTemp → heater LED, with hysteresis · 12 minPRO
  23. 23DC motor speed controlPWM a motor with the pot · 10 minPRO
  24. 24Smart fan controllerTemperature → fan speed · 12 minPRO
  25. 25Ultrasonic distancePing-echo ranging · 11 minPRO
  26. 26Parking sensorCloser = faster beeps · 13 minPRO
  27. 27Radar sweepServo scans, reports distance · 13 minPRO
  28. 28Pedestrian crossingTraffic light + request button · 13 minPRO
  29. 29Two-button dimmerUp / down brightness · 11 minPRO
  30. 30Combination lockA secret button sequence · 14 minPRO

World 5 · Power & Regulation

PROFeeding a circuit properly
  1. 01Where power comes fromWall, battery, USB, sun · 6 minPRO
  2. 02Reading a power ratingWhat "5 V 2 A" promises · 6 minPRO
  3. 03Battery capacity & runtimeWhat mAh really buys you · 7 minPRO
  4. 04Mains & the transformerA ratio, and a gap · 7 minPRO
  5. 05The bridge rectifierBoth halves, one direction · 7 minPRO
  6. 06Smoothing & rippleFilling in the gaps · 7 minPRO
  7. 07The linear regulatorHolding 5 V, whatever happens · 7 minPRO
  8. 08Why regulators run hotThe volts you throw away · 8 minPRO
  9. 09The buck converterStepping down without the heat · 8 minPRO
  10. 10The boost converterMore volts than you have · 7 minPRO
  11. 11Choosing a regulatorLinear, LDO or switching · 7 minPRO
  12. 12Powering an Arduino properlyThree ways in, two of them safe · 8 minPRO

World 6 · Op-Amps & Analog Blocks

PROSmall signals, made useful
  1. 01What an op-amp doesA difference, made enormous · 7 minPRO
  2. 02The two golden rulesAlmost every circuit falls out of these · 7 minPRO
  3. 03The comparatorFeedback removed on purpose · 7 minPRO
  4. 04Hysteresis and the Schmitt triggerTwo thresholds beat one · 8 minPRO
  5. 05The bufferGain of one, and worth every penny · 6 minPRO
  6. 06The non-inverting amplifierGain = 1 + Rf / Rg · 8 minPRO
  7. 07The inverting amplifierGain = −Rf / Rin, and a virtual earth · 8 minPRO
  8. 08The summing amplifierAdding voltages with resistors · 7 minPRO
  9. 09The difference amplifierKeeping the gap, discarding the rest · 8 minPRO
  10. 10Single supply and virtual groundInventing a middle to swing around · 8 minPRO
  11. 11Where the golden rules stopOffset, rails and bandwidth · 8 minPRO
  12. 12Amplifying a sensor signalMillivolts into something a pin can read · 9 minPRO

World 7 · Practical Design

PROChoosing values, not just knowing parts
  1. 01Why 4.7 kΩ and never 5 kΩPreferred values and tolerance · 6 minPRO
  2. 02How much energy a capacitor holdsHalf C V squared, and why the volts matter most · 6 minPRO
  3. 03The Zener diodeA diode that is useful backwards · 7 minPRO
  4. 04The MOSFET as a switchVoltage in, almost no current, very little heat · 7 minPRO
  5. 05RC filtersLetting the slow through, or the fast · 7 minPRO
  6. 06ReactanceResistance that depends on frequency · 6 minPRO
  7. 07The 555 timerTwo resistors, one capacitor, any frequency you like · 8 minPRO
  8. 08Voltage drop in the wiresWhy it works on the bench and not on the robot · 6 minPRO
  9. 09How wide does a PCB track need to be?Copper, current and a temperature rise you choose · 7 minPRO

World 8 · Screens & I²C

PROPutting words on a display, and the two-wire bus
  1. 01The 16×2 character displayNot a screen — a grid of letter-shaped boxes · 6 minPRO
  2. 02Six wires to a screenRS, EN and four data lines — and why four, not eight · 7 minPRO
  3. 03The cursor is the whole APIprint appends, setCursor aims, and nothing wraps · 6 minPRO
  4. 04Why your number leaves a 0 behindThe display never erases anything you did not erase · 6 minPRO
  5. 05Putting a measurement on the screenA sensor, a label, and how often to redraw · 7 minPRO
  6. 06The display that shows nothingThree causes, in the order worth checking · 6 minPRO
  7. 07I²C: two wires, many devicesHow a bus replaces a pin per part · 7 minPRO
  8. 08The same display, on two wiresWhat the I²C backpack actually does · 6 minPRO
  9. 09A clock that keeps time without youAn I²C real-time clock, on the display · 9 minPRO

World 9 · Sensors

PROTemperature and humidity, a joystick, a rotary encoder
  1. 01What a sensor gives youA voltage, a level, or a message · 7 minPRO
  2. 02The DHT22: temperature and humidityOne wire, two readings, and the value that means failed · 8 minPRO
  3. 03Feels like: the heat indexA derived value, and the argument that decides its unit · 7 minPRO
  4. 04The thumb joystickTwo potentiometers, a button, and a dead zone · 8 minPRO
  5. 05The rotary encoderTwo switches a quarter-cycle apart, read by polling · 9 minPRO
  6. 06The encoder on an interruptCatch every edge while the loop is busy · 9 minPRO
  7. 07Smoothing noisy readingsA moving average, and what it costs · 8 minPRO
  8. 08Capstone: a climate displayA DHT22 on the 16×2, with an encoder to change screens · 10 minPRO

World 10 · Pixels & Digits

PROA seven-segment digit and a strip of addressable LEDs
  1. 01The seven-segment digitSeven LEDs in the shape of an 8 · 6 minPRO
  2. 02A digit is a byteOne number per digit, and bitRead to unpack it · 7 minPRO
  3. 03Counting, and a dice you rollThe table, a remainder, a button and random() · 8 minPRO
  4. 04NeoPixels: one wire, many LEDsAddressable LEDs, a buffer, and show() · 8 minPRO
  5. 05Colour by angle: HSVColorHSV, and why a real strip needs gamma32 · 9 minPRO
  6. 06The power budget60 mA a pixel, and why the strip gets its own supply · 8 minPRO
  7. 07Capstone: a level meterA knob, a bar on the strip, the number on the digit · 10 minPRO

World 11 · Internet of Things

PROWi-Fi, HTTP and a cloud that answers back
  1. 01What "connected" actually meansA board, a radio, a router and a server · 7 minPRO
  2. 02Joining a networkWiFi.begin, and waiting for it with a deadline · 8 minPRO
  3. 03Asking for something: HTTP GETbegin, GET, getString, end — and the status number · 8 minPRO
  4. 04Reading an answer by handindexOf, substring and toFloat on a JSON reply · 9 minPRO
  5. 05A switch you are not standing next toPoll the cloud, drive a pin · 8 minPRO
  6. 06Sending data: HTTP POSTPut a reading in the body, read the verdict · 8 minPRO
  7. 07Asking politelyRate limits, and polling with millis() · 9 minPRO
  8. 08Capstone: a connected weather stationYour reading goes up, the forecast comes down · 12 minPRO

World 12 · Motion

PROServos, DC motors, steppers — and the drivers between them
  1. 01Three ways to make things moveAn angle, a speed, or a number of steps · 8 minPRO
  2. 02Why a motor can’t hang off a pinCurrent, back-EMF and the flyback diode · 7 minPRO
  3. 03The H-bridgeFour switches, two inputs, both directions · 9 minPRO
  4. 04Speed and direction togetherPWM on one input — and why you ramp instead of slam · 9 minPRO
  5. 05The stepper motorCoils, 2048 steps, and a library that counts · 10 minPRO
  6. 06Homing with a limit switchGiving a stepper a zero it can trust · 9 minPRO
  7. 07Pan and tilt with a joystickTwo servos, a speed instead of an angle, and a dead zone · 9 minPRO
  8. 08Capstone: a dial-controlled jointAn encoder sets the target, a stepper follows, a switch keeps it honest · 12 minPRO

World 13 · Digital Logic

PROBinary, gates that add, and the decoder behind every display
  1. 01Why digital means two statesVoltage bands, and the margin that makes noise harmless · 8 minPRO
  2. 02Binary is place valueEach bit is worth twice the one to its right · 10 minPRO
  3. 03Hexadecimal: one digit per nibbleWhy programmers write 0xB4 instead of 180 · 7 minPRO
  4. 04De Morgan’s lawsTurning an AND into an OR by inverting everything · 11 minPRO
  5. 05Parity: XOR counts the 1sHow one extra bit catches a flipped one · 7 minPRO
  6. 06The half adderAdding two bits with one XOR and one AND · 10 minPRO
  7. 07The full adderA carry in, a carry out — and columns that chain · 12 minPRO
  8. 08Comparing two numbers in logicEqual means every column matches · 7 minPRO
  9. 09Decoding a number for a displayFour bits in, seven segments out · 12 minPRO
  10. 10Capstone: a 2-bit adding machineToggles in, two full adders, a digit out · 12 minPRO

World 14 · Talk to your Arduino

PROReading what you type into the Serial Monitor
  1. 01The line that goes the other wayavailable(), read(), and one byte at a time · 7 minPRO
  2. 02From characters to a lineCollecting bytes until the newline arrives · 8 minPRO
  3. 03Reading a numberparseInt, and the 0 that nobody typed · 8 minPRO
  4. 04A tiny command languagereadStringUntil, and words that do things · 8 minPRO
  5. 05A command shellOne sketch that takes orders for an LED and a servo · 10 minPRO

World 15 · Soldering & Real Builds

PROMaking a circuit permanent, and fixing it when it goes wrong
  1. 01Tools, heat and safetyWhat you need, and the habits that keep it safe · 8 minPRO
  2. 02A good joint, and a bad oneReading what happened from the shape · 8 minPRO
  3. 03Soldering a through-hole partHeat, feed, solder away, iron away, trim · 8 minPRO
  4. 04Desoldering and fixing mistakesBraid, the pump, and patience with the pads · 7 minPRO
  5. 05From breadboard to a board that lastsPerfboard, stripboard, and planning the layout first · 9 minPRO

World 16 · Raspberry Pi & GPIO

PROA whole computer that can switch a wire
  1. 01What is a Raspberry Pi?A computer the size of a card · 5 minPRO
  2. 02The GPIO headerForty pins, and the two numbers they each have · 7 minPRO
  3. 03Your first blinkFour lines that move a real pin · 8 minPRO
  4. 04Why the LED needs a resistor3.3 volts, and what a pin can actually give · 7 minPRO
  5. 05Sequences and timingLists, loops and a traffic light · 8 minPRO
  6. 06PWM: brightness, not just onSwitching fast enough to fool the eye · 8 minPRO
  7. 07Reading a buttonTurning a pin into an input · 8 minPRO
  8. 08Making soundThe buzzer, and beeping in patterns · 6 minPRO
  9. 09Keeping stateVariables that survive the loop · 7 minPRO
  10. 10When it breaksReading errors instead of guessing · 7 minPRO

World 17 · Build Projects

PROGuided builds: wire a real device step by step, then make it run
  1. 01Turn On Your First LEDOne LED, one line of code · 4 minPRO
  2. 02Your First BlinkOn, off, repeat · 4 minPRO
  3. 03Traffic LightRed, yellow, green — one timed cycle · 12 minPRO
  4. 04Distance AlarmUltrasonic echo → centimetres → alarm · 15 minPRO
  5. 05Night LightLight sensor → PWM brightness · 14 minPRO
  6. 06Morse BeaconLED + buzzer timing pattern · 10 minPRO
  7. 07Candle FlickerRandom PWM glow · 8 minPRO
  8. 08Heartbeat LEDExpressive PWM timing · 8 minPRO
  9. 09RGB Mood LampThree PWM channels, many colors · 12 minPRO
  10. 10Fan Speed ControllerPotentiometer → PWM motor · 12 minPRO
  11. 11Servo GaugeAnalog dial → servo angle · 13 minPRO
  12. 12Temperature WarningTemperature sensor → alert · 15 minPRO
  13. 13Plant Water MeterSoil dial → status LEDs · 13 minPRO
  14. 14Sunrise AlarmPWM fade + buzzer cue · 12 minPRO
  15. 15Parking AssistantUltrasonic distance → beep rate · 16 minPRO
  16. 16Button-Controlled LampDigital input → digital output · 10 minPRO
  17. 17Dimmer KnobPotentiometer → PWM brightness · 11 minPRO
  18. 18DoorbellButton → buzzer tone · 11 minPRO
  19. 19Breathing LEDPWM ramps with a for loop · 12 minPRO
  20. 20Light ThereminLight sensor → buzzer pitch · 13 minPRO
  21. 21Alternating BlinkersTwo LEDs, always opposite · 10 minPRO
  22. 22Cooling FanTemperature → PWM motor · 14 minPRO
  23. 23Barrier GateButton → servo position · 13 minPRO
  24. 24Distance ThereminEcho time → distance → pitch · 12 minPRO
  25. 25LCD ThermometerDHT22 → LCD readout · 16 minPRO
  26. 26Electronic Dicerandom() → segment patterns · 15 minPRO
  27. 27NeoPixel Level MeteranalogRead → how many pixels · 14 minPRO
  28. 28Stepper Seconds HandStepper.h, steps per revolution · 15 minPRO
  29. 29Joystick Camera PanAnalog stick → rate control · 15 minPRO
  30. 30Volume KnobEncoder clicks → counter → display · 18 minPRO
  31. 31Desk ClockDS3231 RTC → LCD · 18 minPRO
  32. 32Greenhouse LoggerDHT22 + Wi-Fi → POST /log · 18 minPRO
  33. 33Remote LampWi-Fi polling → GET /switch · 15 minPRO

World 18 · Circuits & Signals

PRORC and RLC circuits, op-amps and the oscilloscope
  1. 01RC charging and the time constantMeasure τ = RC with an oscilloscope cursor · 10 minPRO
  2. 02The RC low-pass filterFind the −3 dB frequency on the scope · 10 minPRO
  3. 03Series RLC: resonance and ringingTune C for 1 kHz, then damp the ringing · 10 minPRO
  4. 04Op-amp amplifiers and clippingSet a gain of −10 and +10 without clipping · 10 minPRO
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Electronics & ArduinoOhm’s Law Explained: Voltage, Current and LED ResistorsLearn what voltage, current and resistance mean, how Ohm’s law links them, and how to pick the resistor that protects an LED. Includes a live 3D circuit lab.5 min read