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StartElectronics basics: Build your first circuitMake an account
This week

This week: one challenge and a goal.

This week’s challenge+150 XP

Sweep a servo

Nov 9 to Nov 15

Connect a servo's signal wire to pin 9 and swing its arm from one end to the other and back. The Servo library's write() takes an angle from 0 to 180.

What you’ll learnLibraries: the Servo library turns an angle into the pulses a servo understands.

    StartSign in to check your build and earn the XP.
    Practice past challengesNo XP, just practice
    1. Beep SOS in Morse codeFunctions: write a piece of code once, give it a name, and use it as often as you like.
    2. Blink two LEDs at two speedsNon-blocking timing with millis(), so one sketch can do two things at once.
    3. Print a knob's readingHow analogRead() turns a voltage into a number from 0 to 1023, and how to watch it on the serial monitor.
    0/5
    This week0 XP

    5 steps to go

    Courses

    Every course, from your first circuit up.

    Whether you are just starting out or building on what you already know, each one is chapters of lessons, ending in a project you actually finish.

    Career guides

    What do you want to build?

    1 of 3

    Have you built electronics or written code before?

    Electronics basics

    10 h

    A breadboard and a few parts, with one Uno blink at the start and no processor after it. What current, voltage, time and logic really do.

    11 chapters20 lessons

    0 of 20 done

    Embedded on the Arduino Uno

    12 h

    One board, twenty pins and a C++ sketch. From a lamp you switch to a game you can play.

    Arduino Uno R39 chapters16 lessons

    0 of 16 done

    Embedded on the ESP32-C3

    11 h

    A 32 bit RISC-V board at 160 MHz. Its own peripherals, its own 3.3 V rules, and a console at the end of it.

    ESP32-C3-DevKitM-17 chapters13 lessons

    0 of 13 done

    Embedded on the Raspberry Pi Pico

    6 h

    A dual core Cortex-M0+ at 125 MHz. PWM on every pin, a 64 bit clock, and pins that do not forgive 5 V.

    Raspberry Pi Pico4 chapters7 lessons

    0 of 7 done

    Build your own fight stick

    4 h

    One button to a full leverless controller on a Pico: SOCD, eight buttons, lit buttons, an OLED and modes.

    Raspberry Pi Pico2 chapters5 lessons

    0 of 5 done

    Embedded on the STM32F411

    6 h

    A Cortex-M4 at 84 MHz, where a pin is a port and a number and every peripheral starts with its clock switched off.

    STM32F411 Black Pill3 chapters6 lessons

    0 of 6 done

    C++ on a board

    10 h

    The language, one idea per lesson, on a board that shows you what your code did.

    Arduino Uno R35 chapters13 lessons

    0 of 13 done

    Digital logic and memory

    4 h

    Build logic from individual gates, then make a bit persist, count and move through a register.

    2 chapters4 lessons

    0 of 4 done

    Interactive devices on the Uno

    8 h

    Read people and sensors without blocking, control an output, then finish with two playable builds.

    Arduino Uno R34 chapters9 lessons

    0 of 9 done

    From gates to a computer

    16 h

    Start with one NAND gate, package every circuit you build into a chip, and use your chips to build the next one: an adder, memory, a CPU of your own, and a computer that runs your program.

    6 chapters23 lessons

    0 of 23 done

    Build a claw machine

    6 h

    Build a real arcade claw machine piece by piece, from one stepper motor to coins, a clock, a win sensor, lights and sound.

    Arduino Uno R33 chapters8 lessons

    0 of 8 done

    Build a vending machine

    5 h

    Build a real vending machine piece by piece: a keypad, a screen, coins and change, spirals, a drop sensor and service mode.

    Arduino Uno R33 chapters6 lessons

    0 of 6 done

    Build a balance bot

    2 h

    Three lessons on a two-wheel self-balancing robot: read its tilt, see what the wheels do to it, and write the PID that stands it up.

    Arduino Uno R32 chapters3 lessons

    0 of 3 done

    Build a Halloween prop

    5 h

    Five porch props on the Uno, from a fog trigger to a talking skull, each one a complete build with the safety notes that go with it.

    Arduino Uno R33 chapters5 lessons

    0 of 5 done

    Build Christmas lights

    4 h

    Four holiday builds on the Uno, from a star on the tree to a light show synced to a song, each one ready to hang up.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Build a handheld game console

    6 h

    Wire a color screen, buttons and sound to an ESP32-C3, one working step at a time, and finish with three games you can play.

    ESP32-C3-DevKitM-13 chapters7 lessons

    0 of 7 done

    Starter kit companion: the project book

    10 h

    Follows the fifteen projects in the official Arduino Starter Kit book, in its order, each one running in your browser.

    Arduino Uno R34 chapters15 lessons

    0 of 15 done

    Starter kit companion: the 24-lesson kit

    14 h

    Follows the lessons in the Elegoo Uno R3 Super Starter Kit tutorial, in its order, each one running in your browser.

    Arduino Uno R35 chapters24 lessons

    0 of 24 done

    Starter kit companion: the 33-lesson kit

    20 h

    Follows the lessons in the Elegoo Uno R3 Most Complete Starter Kit tutorial, in its order, each one running in your browser.

    Arduino Uno R36 chapters33 lessons

    0 of 33 done

    Build a pocket pet

    4 h

    A Tamagotchi-style pet on an OLED: a screen, buttons, stats, a clock and a memory, ending with Pip.

    Arduino Uno R33 chapters6 lessons

    0 of 6 done

    Build a desk buddy robot

    4 h

    Animated eyes on a round display that blink, feel, react to touch, tilt and light, ending with a robot that misses you.

    ESP32-C3-DevKitM-13 chapters6 lessons

    0 of 6 done

    Model rocket flight computer

    4 h

    Bring up a barometer and an IMU, catch apogee, then fly a full state machine that logs to microSD.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Mars rover

    4 h

    Drive by counting wheel slots, see hazards, do the science, then send your rover on a full mission.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Satellite tracker

    4 h

    Aim a dish with a stepper and a servo, predict a pass from an orbit model, then track it across the sky.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Build a spaceship control panel

    5 h

    Arming switches, a mission display, a countdown, an engine and a master alarm, then fly the whole panel to orbit.

    Arduino Mega 25604 chapters7 lessons

    0 of 7 done

    Build an escape-room puzzle box

    4 h

    A keypad, a magnet key, an RFID card, a tilt sequence and a light puzzle, each one a lesson, then the whole box with its lock.

    Arduino Mega 25603 chapters7 lessons

    0 of 7 done

    Build a pinball table

    5 h

    From two flipper buttons to a full table with a kicker, lights, sound and a saved high score, on a Mega.

    Arduino Mega 25603 chapters5 lessons

    0 of 5 done

    Build a slot machine

    4 h

    Pull a real arcade lever, spin three OLED reels and pay out by a table whose odds you can check, on an Uno.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Build a laser sword

    3 h

    A light saber style sword in three builds: a blade that ignites, motion you can hear, then the whole hilt with a sound font.

    Arduino Uno R31 chapter3 lessons

    0 of 3 done

    Build an arc reactor and helmet

    3 h

    An arc reactor style chest light and a moving faceplate in three builds: the glow, the helmet, then the whole suit.

    Arduino Uno R31 chapter3 lessons

    0 of 3 done

    Build a rhythm game

    3 h

    A rhythm game in three builds: notes that fall in time, buttons that judge your timing, then the whole game with combos and a high score.

    Arduino Uno R31 chapter3 lessons

    0 of 3 done

    Build a 4x4x4 LED cube

    3 h

    Sixty-four LEDs from twenty wires in three builds: a shift register, multiplexing slowed down, then a cube full of animations.

    Arduino Uno R31 chapter3 lessons

    0 of 3 done

    Build lights for the holidays

    3 h

    Four builds on the Uno for New Year’s Eve, Valentine’s Day, Diwali and Hanukkah, each one ready to put in a window.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Sim racing and flight sim controllers

    5 h

    Template a button box, a shifter with a handbrake and a flight panel on a Pro Micro before you buy the parts.

    SparkFun Pro Micro2 chapters4 lessons

    0 of 4 done

    Custom keyboards from the matrix up

    3 h

    Scan a key matrix, see ghosting and the diode that stops it, then add layers, a knob and per-key light.

    SparkFun Pro Micro2 chapters3 lessons

    0 of 3 done

    Home Assistant devices

    5 h

    Build the sensors and switches people put around the house on an ESP32-C3, and see how each reading reaches Home Assistant.

    ESP32-C3-DevKitM-13 chapters5 lessons

    0 of 5 done

    Model railroad electronics

    4 h

    Throw turnouts, run a level crossing, follow a train with block signals and drive a DC loco with momentum, all from an Uno.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    3D printer and CNC basics

    4 h

    Learn what a printer’s firmware does underneath: homing, temperature control with safety, G-code motion and runout detection.

    Arduino Uno R32 chapters4 lessons

    0 of 4 done

    Build a macro pad

    2 h

    Twelve keys, a volume knob, three layers and a screen on a Pro Micro that plugs in as a keyboard.

    SparkFun Pro Micro2 chapters3 lessons

    0 of 3 done

    Build a MIDI controller

    2 h

    Faders, drum pads, a knob and an encoder on a Pro Micro, sending real MIDI bytes you can read.

    SparkFun Pro Micro2 chapters3 lessons

    0 of 3 done

    Build a smart home hub

    3 h

    A web dashboard on an ESP32-C3 that switches relays, reads sensors and runs schedules from a clock.

    ESP32-C3-DevKitM-12 chapters3 lessons

    0 of 3 done

    Build a solar tracker

    2 h

    Light sensors and servos aim a panel, an INA219 measures it, and a fair experiment compares tracked with fixed.

    Arduino Uno R32 chapters3 lessons

    0 of 3 done

    Build a science fair lie detector

    2 h

    Skin response and heart rate against a calm baseline: a science demo of the stress response, not a real lie detector.

    Arduino Uno R32 chapters3 lessons

    0 of 3 done

    Build a guitar controller

    1 h

    A rhythm game guitar on a Pro Micro in three short lessons: frets and a strum bar that never double-strums, a whammy and star power, and your own config.

    SparkFun Pro Micro2 chapters3 lessons

    0 of 3 done

    Build load cell pedals

    1 h

    Sim racing pedals on a Pro Micro in three short lessons: a load cell brake on an HX711, a hall throttle and a pot clutch, and the curve that makes it feel right.

    SparkFun Pro Micro2 chapters3 lessons

    0 of 3 done

    Build a camera slider

    1 h

    A motorized camera slider on a Nano in three short lessons: homing a stepper, an eased video move, and a timelapse that settles before every shot.

    Arduino Nano2 chapters3 lessons

    0 of 3 done

    Talk to chips: I2C, SPI and UART

    4 h

    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.

    Arduino Uno R35 chapters7 lessons

    0 of 7 done

    Motors and motion

    4 h

    DC motors on a driver, the H bridge inside it, servos, a stepper on an A4988, an encoder that measures what the motor did, and a 2WD robot car with ultrasonic eyes and line sensors.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Servos, solenoids and actuators

    6 h

    Everything that moves a thing to a place: servo pulses measured and calibrated, big servos and their supply, easing curves, solenoids with a flyback diode, linear actuators, vibration motors, and an animatronic face on a PCA9685.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Power and batteries

    3 h

    Where the volts come from and how to keep them: Ohm's law on a real meter, cells in series and parallel, a regulator, a LiPo on a TP4056, a boost converter, a battery gauge, and a power bank you build yourself.

    5 chapters7 lessons

    0 of 7 done

    Wire, fuses and breakers

    5 h

    Why wire gets hot and how to stop it: copper resistance, ampacity, voltage drop, fuse curves, thermal and magnetic breakers, coordination, and a 12 V camper circuit you size yourself.

    7 chapters7 lessons

    0 of 7 done

    Transformers in practice

    5 h

    The iron box between the wall and your project, measured: turns ratio, VA ratings, center taps, regulation under load, isolation, and the 24 V control transformer in every furnace.

    7 chapters7 lessons

    0 of 7 done

    MicroPython on the Pico

    3 h

    Real Python on a Raspberry Pi Pico: blink and the REPL, buttons and if, loops and PWM, a knob on the ADC, lists and functions on an LED bar, an OLED on I2C, and a reaction game boss.

    Raspberry Pi Pico4 chapters7 lessons

    0 of 7 done

    MicroPython on the ESP32

    5 h

    Python on an ESP32 DevKit: the REPL and blink, pins and PWM, the ADC, timers and interrupts, I2C sensors, WiFi in five lines, and a lamp you switch from a web page.

    ESP32 DevKit V14 chapters7 lessons

    0 of 7 done

    Python from zero

    5 h

    Beginner Python on a Raspberry Pi: print, variables, decisions, loops, lists, functions, dicts and strings, then a button with gpiozero and a working pedestrian crossing.

    Raspberry Pi 4 Model B4 chapters7 lessons

    0 of 7 done

    Python with real habits

    6 h

    Advanced Python on a Raspberry Pi, after Python from zero: modules, classes, exceptions, files and logging, tests with plain assert, generators, and a sensor logger that uses them all.

    Raspberry Pi 4 Model B4 chapters7 lessons

    0 of 7 done

    Transistors and op-amps for real

    4 h

    Intermediate, after Electronics basics: the diode curve, biasing a BJT, common-emitter gain, the MOSFET as switch and resistor, op-amp gain both ways, comparators with hysteresis and split supplies.

    3 chapters7 lessons

    0 of 7 done

    AC, signals and filters

    4 h

    Advanced, after Transistors and op-amps for real: sine, peak and RMS, reading a scope, RC and RL filters, frequency response, RLC resonance and active filters.

    3 chapters7 lessons

    0 of 7 done

    Sensors and measurement

    4 h

    Intermediate: thermistors and RTDs, strain gauges in a Wheatstone bridge, light and IR, current on a shunt and an INA219, ADC resolution and noise, and calibration, finished with a power instrument you check against Ohm's law.

    Arduino Uno R33 chapters7 lessons

    0 of 7 done

    Relays, contactors and motor control

    4 h

    Intermediate, the electrician's course: relay coils and flyback diodes, latching start/stop circuits, interlocks, three-way switching, timers and ladder logic, all at low voltage, finished with a start/stop station and an emergency stop you wire yourself.

    4 chapters7 lessons

    0 of 7 done

    Power electronics

    4 h

    Advanced: switches, inductors and heat: buck and boost converters from loose parts, PWM, MOSFET drivers, H bridges, efficiency, and a regulated supply you set from its formula.

    4 chapters7 lessons

    0 of 7 done

    Circuit design capstone

    4 h

    Expert: take one product from a written requirement to a tested board: blocks, a schematic worked out on paper, part choice, simulating the corners, PCB layout, a test plan, and a revision that fixes what the tests found.

    3 chapters7 lessons

    0 of 7 done

    Connected devices

    4 h

    WiFi, APIs, a web server, MQTT, ESP-NOW and BLE on the ESP32, and a device that keeps going when the network does not.

    ESP32 DevKit V14 chapters7 lessons

    0 of 7 done

    MQTT in depth

    6 h

    Topics and wildcards, QoS, retained messages and last wills, a broker of your own, Home Assistant discovery and security, built as real code on the Raspberry Pi, and two devices that talk only through the broker.

    Raspberry Pi 4 Model B4 chapters7 lessons

    0 of 7 done

    Breadboard to PCB

    3 h

    Take three working circuits from the breadboard to a finished board: the schematic, footprints, placement, routing, design rules, and what a board house needs.

    3 chapters6 lessons

    0 of 6 done

    Fix the bug

    1 h

    Short puzzles on an Uno: one planted fault each, in the wiring or the code. Find it, fix it, and see it work.

    Arduino Uno R32 chapters8 lessons

    0 of 8 done

    Debug like an engineer

    2 h

    The multimeter, the oscilloscope, the logic probe and analyzer, Serial done right, and a method that finds any fault. Ends with a boss: three bugs in one circuit.

    Arduino Uno R33 chapters6 lessons

    0 of 6 done

    C++ that scales

    6 h

    The habits that keep a big program sane, on the Uno: references and const, classes, a ring buffer, a state machine class, templates, and logic split from pins so it tests itself. Ends with a tested calculator.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Under the hood

    5 h

    Take the Arduino wrapper off: DDR, PORT and PIN, Timer 1 by hand, the vector table and interrupts, cycle-counted delays in a .S file, a bug read off a halt in the debugger, and a UART drawn by hand on a pin.

    Arduino Uno R34 chapters6 lessons

    0 of 6 done

    Scheduling and RTOS

    6 h

    From a scheduler written by hand to FreeRTOS on the Uno: tasks and priorities, time slicing on the logic analyzer, queues, mutexes and priority inversion, starvation and the watchdog, and a four-task device.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Low power products

    6 h

    Make a battery last years: where an Uno’s current goes, sleep modes and wake sources, a power budget on a bare chip, measuring with a meter and an INA219, battery life checked against a draining cell, and a coin cell node.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Electrical safety for every bench

    5 h

    How shock harms, voltage classes, fuses, lockout and tagout, testing before you touch and battery fire, on low-voltage stand-ins you can break safely, then a guarded press to inspect.

    4 chapters7 lessons

    0 of 7 done

    How a house is wired

    6 h

    From the service and the meter to the panel, branch circuits, hot neutral and ground, three-way and four-way switches and GFCIs, all on low-voltage models you can break safely.

    5 chapters8 lessons

    0 of 8 done

    Reading electrical drawings

    5 h

    Symbols, schematics, wiring diagrams, ladder diagrams, one-lines, floor plans and panel schedules, each read on the page and then proved on a circuit that runs.

    6 chapters8 lessons

    0 of 8 done

    Math for electronics

    6 h

    Metric prefixes, scientific notation, Ohm's law rearranged, ratios and tolerance, watts and squares, RMS and decibels: every answer set on a real part and proved on a meter, ending in a component calculator.

    5 chapters8 lessons

    0 of 8 done

    PLCs and ladder logic

    7 h

    How factory machines think: the scan cycle, contacts and coils, seal-in circuits, timers, counters and sequencers, ending on a crossing controller you design rung by rung.

    Arduino Uno R35 chapters8 lessons

    0 of 8 done

    Measurement and instruments

    6 h

    How far to trust a reading: resolution and accuracy, meter loading, bandwidth and the x10 probe, triggering, counters, bus decoding, and an error budget for a real gauge.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    C from zero

    7 h

    The language under every microcontroller, from a first hello over serial: types and sizes, overflow, if and switch, loops, functions and pointers, arrays and strings. Ends with a serial quiz you build and make your own.

    Arduino Uno R34 chapters8 lessons

    0 of 8 done

    Troubleshooting like a technician

    6 h

    Find faults nobody planted for you: power first, half splitting, signal tracing, opens and shorts, failed parts and intermittents. Ends with a repair ticket: three boards, one fault each.

    4 chapters7 lessons

    0 of 7 done

    Data structures and algorithms

    6 h

    The ideas every programmer is asked about, built and measured on an Uno: big O, linked lists, stacks and queues, hash maps, sorting and binary search. Ends with a leaderboard that needs them all.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Software design and testing

    7 h

    How teams keep firmware right as it grows: readable code, modules behind narrow interfaces, fakes, tests on boot, test-first fixes, safe refactors and code review. Ends with a messy sketch refactored under test.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Control systems: PID

    7 h

    Feedback control on real physics: open and closed loops, P, I and D one at a time, tuning by the numbers, encoders, a balancing robot, and a motor that holds its speed whatever you throw at it.

    Arduino Uno R35 chapters7 lessons

    0 of 7 done

    Firmware architecture

    7 h

    How a whole device is put together on the Uno: a scheduler and state machines, ISRs that only record, drivers behind interfaces, checked settings in EEPROM, error codes and the watchdog, safe updates, and a layered multi-sensor boss.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Read datasheets and schematics

    6 h

    The skill every hardware job asks for: schematic symbols, a first page, absolute maximum ratings, timing diagrams, register maps and pinouts, each checked on real parts. Ends with a sensor brought up from its datasheet alone.

    Arduino Uno R34 chapters7 lessons

    0 of 7 done

    Portfolio and interviews

    3 h

    Turn finished projects into a job search: choose and document portfolio pieces, share links that run, read job posts and answer technical questions out loud.

    3 chapters6 lessons

    0 of 6 done

    Software capstone: your own project

    8 h

    The end of the Coding track: design and ship a project of your own on a Raspberry Pi, milestone by milestone, from the problem and the spec through modules, slices, tests and polish to a demo you can share.

    Raspberry Pi 4 Model B4 chapters7 lessons

    0 of 7 done

    Firmware capstone: your own device

    8 h

    Take your own device from an idea to a tagged release: a brief, testable requirements, a layered architecture, a driver from the datasheet, self-tests and unit tests, a watchdog and a power budget, then the write-up.

    ESP32-C3-DevKitM-14 chapters7 lessons

    0 of 7 done

    IoT capstone: your own connected product

    8 h

    Design and build a connected product of your own on the ESP32-C3, milestone by milestone: the brief, the data contract, firmware, a dashboard, failure handling, a security review and a demo.

    ESP32-C3-DevKitM-14 chapters7 lessons

    0 of 7 done

    Robotics capstone: your own machine

    7 h

    Pick a mobile robot or an arm and build it through seven milestones: a brief, sensors, closed-loop motion, control, safety, testing, and a demo and write-up for your portfolio.

    3 chapters7 lessons

    0 of 7 done

    Technician capstone: your own repair bench

    7 h

    Faulty units come in, and you send them back working: intake, a diagnosis plan, schematic reading, repair, verification, a repair log and a customer report, with the meter, the scope and the component tester.

    3 chapters7 lessons

    0 of 7 done

    Electrician capstone: plan a small shop

    7 h

    Plan a small woodshop end to end on low-voltage models: scope, load calculation, panel schedule, a seal-in control circuit, a motor starter with overload, an inspection test and a portfolio write-up.

    3 chapters7 lessons

    0 of 7 done

    Maker capstone: your own invention

    7 h

    Invent a gadget of your own and take it from a blank page to a shared demo: find an idea, plan it, prototype, iterate, make it robust, document it and share it, each milestone practiced on real gallery builds first.

    Arduino Uno R33 chapters7 lessons

    0 of 7 done

    The twelve week course

    24 h

    The classroom course, week by week: a loop on a breadboard through to a board talking over serial.

    3 chapters12 lessons

    0 of 12 done

    Leaderboard

    This week, by experience.

    Experience earned since Monday, by everyone who has not unticked the box.

    See all leaderboards

    The weekly board needs an account.

    Make an account
    Rewards

    Badges for the steps you take.

    First light

    Light an LED. Wire one up, press Run and watch it come on.

    Not yet

    Compiled in the browser

    Compile your own code. Press Run on a board with a sketch in the editor.

    Not yet

    555 astable

    Get a 555 running. Its output has to go high and low on its own.

    Not yet

    Found the fault

    Fail a Check, work out why, and pass it.

    Not yet

    Every board

    Run the Uno, the ESP32-C3, the Pico and the STM32 at least once each.

    Not yet

    Lesson published

    Write a lesson in the editor and publish it.

    Not yet

    In a class

    Join a class with the code your teacher gives you.

    Not yet

    Seven days

    Pass a step on seven days in a row.

    Not yet

    Milestones

    Achievements for the big ones.

    First wire

    Drag from one pin to another.

    Not yet

    First Run

    Press Run.

    Not yet

    Ten parts

    Build something with ten parts in it.

    Not yet

    Four families

    Place the Uno, the ESP32-C3, the Pico and the STM32.

    Not yet

    Night owl

    Run something between midnight and four in the morning.

    Not yet

    Early bird

    Run something between four and seven in the morning.

    Not yet

    It spoke

    Get a board to print something.

    Not yet

    Long run

    Leave a simulation going for a minute of its own time.

    Not yet

    Guides

    Read the basics at your own pace.

    Here to meet you wherever you are: the longer tutorials and the roundups each also come as a one-page PDF lesson plan you can download and hand to a class.

    Tutorials and explainers

    Connect a Board to WiFi and Serve a PageHow to Use a Breadboard: Your First CircuitOhm's Law, in a Circuit You Can RunPicking a Resistor for an LEDPull-Up Resistors and the Floating Input They FixDebouncing a Button: Why It Fires More Than OncePWM: Faking an Analog Voltage on a Digital PinThe 555 Astable: Timed by a Capacitor, Not a CrystalLogic Gates, and the Truth Table You Can PressShifting a Byte In, One Edge at a TimeBlink an LED with Arduino: Wiring and the ResistorArduino Button Debounce: See the Bounce, Then Fix ItArduino Blink Without Delay: Two LEDs, Two RatesArduino PWM Fade: analogWrite, Pins and the CurveBlink an LED on the ESP32-C3, Step by StepBlink an LED with a 555 Timer, No MicrocontrollerArduino Simulators Compared: An Honest RoundupHow to Simulate an Arduino Project Without HardwareMeasure It: Read a Circuit With a Scope and PlotterUART Serial Explained: Baud, Frames and the WireI2C Explained: Addresses, Acknowledges and Pull-UpsSPI Explained: Clock, Data and Chip SelectInterrupts vs Polling on Arduino, Side by SideArduino State Machine: A Four-State Reaction GameESP32 HTTP GET Request: Fetch the Weather as JSONESP32 analogRead: 12 Bits, Attenuation and ADC2Raspberry Pi Pico PWM: Slices, Channels and 1 kHzSTM32 Blue Pill Blink with Registers, Not pinModeArduino Uno vs ESP32 vs Pico: Which to Learn First?Multisim Live Is Gone: A Chromebook AlternativeDigital Electronics on Chromebooks: Labs by UnitHalf Adder and Full Adder: Truth Table to BreadboardFlip-Flops Explained: SR Latch, D and JK Flip-FlopsScience Olympiad Circuit Lab: Free Study Guide, B/CCircuit Lab Practice Test: 30 Questions and AnswersHow to Use a Multimeter: Practice on a Virtual OneArduino Science Fair Projects With a Real HypothesisReaction Time Science Fair Project With an ArduinoEngineering Science Fair Project: How to Write It Up555 Timer Projects for a Science Fair (No Coding)Circuit Lab Division B: Middle School Starter GuideCircuit Lab Division C: High School Study GuideCircuit Lab Cheat Sheet: Every Formula, Worked OutSkillsUSA Electronics Technology Practice CircuitsTSA Electrical Applications: Practice CircuitsArduino Simulator for Chromebook, Free in ChromeArduino Simulator for Mac, Free in Safari or ChromeFree Circuit Simulator for High School ClassesArduino Projects for Beginners, Each One RunningOnline SPICE Simulator: Run and Export NetlistsArduino LED Not Lighting Up or Dim: What to CheckArduino Compile Errors Explained, With the FixesHow to Debug Arduino Code: Prints to BreakpointsResistor Color Code Calculator and Chart"Was Not Declared in This Scope" in Arduino: 6 FixesArduino "expected ';' before" and Similar ErrorsArduino stk500_getsync() Not in Sync: Upload FixesArduino "exit status 1": Find the Real ErrorESP32 DevKit V1 Pinout: Every Pin and Which to AvoidESP32-C3 SuperMini Pinout: LED, ADC, I2C, Boot PinsWemos D1 Mini Pinout: D0-D8 to GPIO, I2C and SPINodeMCU Pinout: ESP8266 D0-D8 to GPIO, Pins to AvoidArduino Nano Pinout: PWM, I2C, SPI, A6 and A7Arduino Uno R4 WiFi Pinout: Every Pin and Its LimitsRaspberry Pi Pico Pinout: GPIO, PWM, ADC and PowerESP32-S3 Pinout: DevKitC-1 Pin Table, Pins to AvoidArduino Uno Pinout: ATmega328P Pins, PWM, I2C, SPIArduino Mega 2560 Pinout: PWM, Serial, I2C, SPIRaspberry Pi Pico W Pinout: GPIO, LED and WiFi PinsXIAO ESP32-C3 Pinout: D Pins to GPIO, ADC, Boot PinsPro Micro Pinout: 32U4 Pins for Arduino and QMKESP-01 Pinout: GPIO0, GPIO2, Boot Modes and I2CSTM32 Blue Pill Pinout: 5 V Tolerant Pins and BOOTATmega328P Pinout: 28-Pin DIP to Arduino PinsWemos D1 R32 Pinout: Uno Names to ESP32 GPIOsCheap Yellow Display Pinout: CYD Screen, Touch, LEDTTGO T-Display Pinout: Screen, Buttons, ADC, I2CXIAO RP2040 Pinout: D Pins to GPIO, LEDs, NeoPixelRP2040-Zero Pinout: All 23 Pins, NeoPixel, PWM, ADCI2C Scanner for Arduino and ESP32, and FixesESP32 Not Connecting to WiFi: Causes and FixesArduino millis() Overflow: Why Subtraction WorksArduino Serial Monitor Garbage or Blank: FixesArduino "Low Memory Available" and "Sketch Too Big"Arduino map() Function: Scale Any ReadingArduino for Loop: Count, Repeat, Chase LEDsArduino Array: Lists of Pins, Patterns and NotesArduino Functions: Write It Once, Call It AnywhereArduino Serial Read: Input from the Serial MonitorArduino Random Numbers: random() and randomSeed()Arduino switch case: Modes, Menus and breakArduino if else: One Branch Runs, and WhyArduino while Loop: Wait, Repeat, Break OutArduino String: Join, Compare, Convert, SplitArduino digitalRead(): Buttons, HIGH and LOWArduino Data Types: int, long, float and byteArduino Serial.print vs println, and DecimalsArduino const vs #define: Which One to UseArduino Struct: Group Values, With ExamplesArduino Pointers Explained: & and * on an UnoArduino enum: Named States, enum class and SwitchArduino Bitwise Operators and bitRead, ExplainedArduino 2D Array: Rows, Columns and StringsArduino sprintf and Float to String, With ExamplesArduino No Matching Function for Call To: FixesArduino Timer Interrupt: Timer1 Every SecondArduino Watchdog Timer: Reset a Stuck SketchArduino Button Counter: Count Presses, Not BouncesArduino AI Assistant in Your Browser: Meet Mokxi AIFix Arduino Code With AI, and Know It CompilesChatGPT for Arduino Code, and an AI That CompilesESP32 PWM: ledcAttach, ledcWrite and FrequencyESP32 Preferences Library: Save Settings, ExampleESP32 Interrupts: attachInterrupt and DebounceESP32 I2C Pins: SDA 21, SCL 22, and Custom PinsArduino Multitasking With millis(), Step by StepArduino Moving Average: Smooth analogRead ValuesArduino Static Variable vs Global, With ExamplesArduino strtok: Parse Serial Commands and CSVArduino "expected unqualified-id": Causes and FixesArduino "stray '\302' in program": How to FixArduino "expected primary-expression": FixesFix "lvalue required as left operand of assignment"Arduino MOSFET Module: Why the IRF520 Is Half OnArduino Relay Module: Active LOW and Startup ClicksHow Many LEDs Can One Arduino Pin Drive?Arduino I2C LCD Not Working: Blank, Blocks, No TextLM2596 Buck Converter: Power an Arduino From 12 VArduino DC Motor: Transistor Wiring and PWM SpeedArduino Battery Level Indicator: 18650 on A0DIY Fight Stick on an Arduino Pro MicroLeverless Controller Build: Buttons, Pins and CodeSOCD Cleaning Explained, With CodeArcade Button Wiring for a Pro Micro or PicoDesign Your Own Fight Stick or Leverless ControllerDesign Your Sim Racing Button Box in the BrowserPrototype Your Keyboard Matrix Before You SolderHome Assistant and ESPHome Devices on an ESP32Arduino Model Railroad: Turnouts, Crossings, Signals3D Printer Firmware: Homing, PID, G-code, RunoutDIY Rhythm Game Controller: Guitar and Dance PadDIY Load Cell Pedals and Flight Stick on a Pro MicroDIY Stream Deck and Camera Slider With ArduinoArduino Eurorack CV Quantizer With a PWM DACOhm's Law Calculator: Volts, Amps, Ohms and WattsArduino EEPROM: Read, Write, put() and get()Arduino Flame Sensor: Wiring, Code and RangeArduino MQ-2 Gas Sensor: Wiring, Warm-Up and CodeArduino Rain Sensor: Wiring, Code and ReadingsArduino FSR: Force Sensor Wiring, Code, ReadingsArduino Flex Sensor: Wiring, Code and AnglesArduino pinMode(): OUTPUT, INPUT and INPUT_PULLUPArduino delayMicroseconds: Max Value and AccuracyArduino Interrupts: attachInterrupt on Pin 2 and 3Arduino millis(): Timers and Multiple TasksArduino PWM Frequency: 490 Hz, 980 Hz, How to ChangeAccelStepper Arduino Library: Examples and HomingStepper Motor Vibrating but Not Turning: FixesA4988 Pinout: Pins, Microstep Table and VrefArduino DRV8825: Wiring, Code and MicrosteppingStepper Motor Wiring: 4, 5 and 6 Wire MotorsRaspberry Pi Pico MicroPython in Your BrowserESP32 MicroPython Simulator, Free in Your BrowserCircuitPython Simulator for the Raspberry Pi PicoRaspberry Pi GPIO with Python, in Your Browser"Does Not Name a Type" Arduino Error: How to Fix ItArduino "No Such File or Directory": How to FixArduino "Redefinition of void setup()": FixesArduino "Undefined Reference To": Every Cause"Function-Definition Is Not Allowed Here" FixArduino "Has No Member Named": Causes and FixesArduino "expected '}' at end of input": How to FixArduino "cannot convert 'String' to 'const char*'"Arduino "control reaches end of non-void function"Arduino "variable or field declared void": FixesArduino "invalid types for array subscript": FixArduino "call of overloaded is ambiguous": FixesATtiny85 Pinout: PB0 to PB5, ADC, PWM, I2C and ISPArduino Leonardo Pinout: I2C, SPI on ICSP, A6-A11STM32F411 Black Pill Pinout: PC13, KEY and BOOT0Arduino Nano ESP32 Pinout: D Pins to GPIO NumbersArduino Pro Mini Pinout: A4 to A7, FTDI, RAW, VCCESP32 DevKitC Pinout: All 38 Pins and the Flash SixArduino Assembly Language: AVR Assembly OnlineSTM32 HAL and Register Code in the BrowserExport a Circuit to a KiCad SchematicArduino Build Guide and Parts Shopping ListBuild a Computer From NAND Gates, Step by StepFollow Your Arduino Starter Kit in the BrowserDigital Logic Lab Experiments, Graded in the BrowserMicrocontroller Lab Experiments With No KitsElectrical Circuits Lab Online, With Graded ChecksVirtual Electronics Lab for College ClassesFree Arduino Simulator for Students, in the BrowserMicrocontroller Lab Viva Questions, With AnswersElectronics Lab Report Template, With an ExampleArduino Practical Exam Practice: Ten Timed TasksESP32 IoT Projects for Final Year StudentsArduino Mini Projects for Engineering StudentsArduino Temperature Data Logger Lab, Step by StepRun an Electronics Lab for Online ClassesArduino Simulator: Serial Monitor and Logic AnalyzerArduino Halloween Props to Build in Your BrowserArduino Christmas Lights to Build in Your BrowserArduino Holiday Projects for Every CelebrationSimulate Two Arduinos Talking Over SerialSimulate an ESP32 and an Arduino Uno TogetherArduino SPI Master and Slave, SimulatedVoltage Divider Simulator With a Real MeterRC Filter Simulator With a Bode PlotNPN Transistor Switch SimulatorOp-Amp Amplifier Simulator, Gain of 10LED I-V Curve, Simulated and Swept555 Timer Simulator: an LED BlinkerArduino Game Projects You Can Play in Your BrowserZener Diode Voltage Regulator Circuit, SimulatedRLC Circuit Simulator: Series Resonance and Q, LiveActive Low Pass Filter With an Op-Amp, SimulatedBCD to 7 Segment Decoder: CD4511 Truth Table, LiveTinkercad ESP32 Simulator: A Free AlternativeWokwi vs Tinkercad: Which Arduino Simulator to UseESP32 Projects for Beginners You Can Run Right NowRobotics Lesson Plans for Middle and High SchoolSTEM Club Ideas: Electronics and Coding SessionsBest ESP32 Simulator? The Free Options, ComparedTinkercad Alternatives: 6 Simulators, ComparedWokwi Alternatives for Arduino and ESP32, ComparedBest Logic Gate Simulator: Free Tools ComparedBest Free Circuit Simulator: 7 Options Compared

    Electronics fundamentals, each with a circuit to poke

    Voltage Dividers and Why They Are Bad Power SuppliesSeries vs Parallel Circuits, Seen With LEDsThe RC Time Constant, on an OscilloscopePWM to an Analog Voltage With an RC FilterDiodes for Reverse Polarity ProtectionNPN Transistor as a Switch: a 2N2222 and an ArduinoThe Flyback Diode, and the Spike It StopsMOSFET vs BJT: Which Transistor to Switch WithAnalog vs Digital Pins, and ADC ResolutionThe 555 Monostable: One Press, One Timed PulseAn Op-Amp as a Comparator, With HysteresisThe Non-Inverting Op-Amp Amplifier, on a Scope
    Build along

    Project tutorials that run as you read.

    The Arduino projects everybody builds, from a traffic light to an ultrasonic sensor, each one running at the top of its page with the wiring, the code and the common mistakes.

    Arduino Traffic Light Code with a Pedestrian ButtonIntermediateArduino Servo Motor with a PotentiometerBeginnerArduino Ultrasonic Sensor (HC-SR04) TutorialIntermediateArduino LCD I2C 16x2: Wiring, Code, Scrolling TextIntermediateArduino DHT22 and DHT11: Temperature and HumidityIntermediateArduino 4x4 Keypad Code Lock with a RelayAdvancedArduino 7 Segment Display: an Electronic DieIntermediateArduino Stepper Motor: 28BYJ-48 and ULN2003IntermediateArduino OLED Display (SSD1306) TutorialIntermediateArduino MPU6050: Accelerometer and TiltIntermediateArduino Potentiometer Wiring and Code: Dim an LEDBeginnerArduino LDR Night Light (Photoresistor)BeginnerArduino IR Remote: Decode NEC, Switch LampsIntermediateESP32 NeoPixel (WS2812B) Rainbow TutorialIntermediateArduino Joystick Module: Wiring, Code, Live DemoIntermediateArduino TMP36 Temperature Sensor in °F and °CIntermediateArduino L293D Motor Driver: Forward and ReverseIntermediateArduino Buzzer and Piezo: Beeps, Notes, MetronomeBeginnerArduino MAX7219 8x8 LED Matrix: Wiring and CodeIntermediateArduino DS3231 Clock With a TM1637 DisplayIntermediatePIR Motion Sensor: How It Works, With an ArduinoBeginnerArduino RC522 RFID Reader: Wiring and CodeIntermediateArduino HX711 Load Cell: Calibration and CodeIntermediateArduino Soil Moisture Sensor: Code and WiringIntermediateArduino DS18B20 Temperature Sensor: Wiring and CodeIntermediateArduino L298N Motor Driver: Wiring, Jumpers and CodeIntermediateArduino A4988 and NEMA 17 Stepper: Wiring and CodeIntermediateArduino Sound Sensor (KY-038): Clap SwitchBeginnerArduino Obstacle Avoiding Robot: Code and WiringIntermediateArduino 4 Digit 7 Segment Display: Wiring and CodeAdvancedArduino nRF24L01: Wiring, Code and a Radio DoorbellAdvancedArduino PCA9685 Servo Driver: Wiring and CodeAdvancedArduino ILI9341 TFT Display: Wiring and CodeAdvancedArduino SD Card Module: A GPS Data LoggerAdvancedArduino IR Transmitter: Laser Tag With Two NanosIntermediateArduino HC-05 Bluetooth: Wiring, Code, AT CommandsBeginnerArduino NEO-6M GPS: Wiring, TinyGPS++ and CodeBeginnerArduino SIM800L: Send and Receive SMS, AT CommandsBeginnerArduino RGB LED: Wiring and Color Mixing CodeBeginnerArduino Rotary Encoder (KY-040): Wiring and CodeBeginnerArduino NeoPixel (WS2812B): Wiring and CodeBeginnerArduino LCD 16x2 Without I2C: Wiring and CodeBeginnerArduino 10k Thermistor: Wiring and CodeIntermediateArduino Tilt Sensor (SW-520D): Wiring and CodeBeginnerArduino Water Level Sensor: Wiring and CodeBeginnerArduino VL53L0X Distance Sensor: Wiring and CodeBeginnerArduino MAX6675 Thermocouple: Wiring and CodeBeginnerArduino Water Flow Sensor (YF-S201): Code and WiringBeginnerArduino Hall Effect Sensor (49E): Wiring and CodeBeginnerArduino Tone Melody: Play a Song on a PiezoBeginnerArduino TM1637 Display: Library and CountdownBeginnerArduino Line Follower Robot: Code and CircuitIntermediateArduino PCF8574 and MCP23017 I/O ExpandersIntermediateArduino BH1750 Light Sensor: Lux, Wiring, CodeBeginnerArduino CD74HC4067 Multiplexer: 16 Analog InputsIntermediateArduino Fingerprint Sensor: Door Lock CodeIntermediateArduino MAX30102 Pulse Oximeter: Code and WiringIntermediateArduino IR Obstacle Sensor (FC-51): Wiring, CodeBeginnerArduino RCWL-0516 Microwave Radar SensorBeginnerArduino DFPlayer Mini MP3 Player: Wiring and CodeIntermediateArduino DS1302 RTC: an Alarm Clock With CodeIntermediateArduino BMP180: Pressure, Altitude and CodeIntermediateArduino MLX90614: Non-Contact IR ThermometerBeginnerArduino Pulse Sensor: Heart Rate on an OLEDIntermediateArduino Color Sensor: TCS34725 Candy SorterIntermediateArduino BME680: Air Quality, Gas and WeatherIntermediateArduino MAX31855: K-Type Thermocouple CodeIntermediateArduino ST7735: 1.8 Inch Color TFT Wiring and CodeAdvancedArduino Nokia 5110 LCD: Wiring, Contrast and CodeAdvancedArduino E-Paper Display: GxEPD2 on a 2.9 Inch PanelIntermediateArduino TM1638: LED&KEY Display, LEDs and ButtonsIntermediateArduino Thermal Printer: Wiring, Code and BarcodesBeginnerArduino MPR121: 12-Key Capacitive Touch PianoBeginnerArduino Self-Balancing Robot: MPU6050 and PID CodeAdvancedArduino ACS712 Current Sensor: Wiring and CodeBeginnerArduino 0-25 V Voltage Sensor: Wiring and CodeBeginnerArduino FC-28 Soil Moisture Sensor: Wiring and CodeBeginnerArduino Vibration Sensor (SW-420): Wiring, CodeIntermediateArduino Touch Sensor (TTP223): Wiring and CodeIntermediateArduino Reed Switch: Wiring, Code and a Door AlarmBeginnerArduino Laser Module (KY-008): Wiring and CodeBeginnerLM358 Op-Amp Simulator: Pinout, Gain and ComparatorIntermediateULN2003 Simulator: Darlington Driver and COM PinBeginnerArduino PZEM-004T and ZMPT101B AC Energy MeterIntermediateArduino AD8232 ECG: Heart Monitor on a PlotBeginnerESP32 ILI9488 3.5 Inch TFT with TFT_eSPIIntermediateArduino ADXL345: Library, Example Code and TiltIntermediateArduino INA219: Current Sensor Library and CodeAdvancedArduino SHT31: Library, Example and WiringIntermediateArduino TB6612FNG: Wiring, Library and CodeIntermediateArduino LCD 20x4: I2C Example Code and LibraryIntermediateArduino GC9A01: Round Display Library and ExampleIntermediateArduino LM35: Temperature Sensor Code and WiringBeginnerESP32 Servo Motor: Wiring and LEDC CodeBeginnerRaspberry Pi Pico Button: Wiring and CodeBeginnerArduino Simon Says Game: Four LEDs, Four ButtonsAdvancedArduino Snake Game on an 8x8 LED Matrix (MAX7219)AdvancedArduino Whack-a-Mole Game: LEDs, Buttons, ScoreIntermediateArduino Stacker Arcade Game on Two LED MatricesAdvanced
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