Start here if you have never wired anything. LEDs, buttons, serial — the rites of passage.

Blink LEDbasicsbeginnerRead & run →Button ControlbasicsbeginnerRead & run →Fade LEDbasicsbeginnerRead & run →I2C EEPROM Read/WritecommunicationintermediateRead & run →I2C RTC Clock (DS1307)communicationintermediateRead & run →I2C Scanner (TWI)communicationintermediateRead & run →KY-040 Rotary EncoderbasicsbeginnerRead & run →LCD 20×4 DisplaydisplaysintermediateRead & run →Multi-Protocol DemocommunicationadvancedRead & run →RGB LED ColorsbasicsintermediateRead & run →Serial Echo (USART)communicationbeginnerRead & run →Serial Hello WorldcommunicationbeginnerRead & run →Serial LED ControlcommunicationbeginnerRead & run →Simon Says GamegamesadvancedRead & run →SPI Loopback TestcommunicationintermediateRead & run →TFT ILI9341 DisplaydisplaysintermediateRead & run →Traffic LightbasicsbeginnerRead & run →

WiFi, BLE, sensors and displays on the ESP32 family — the same chips that ship in our kits.

ESP32-C3: Blink LEDbasicsbeginnerRead & run →ESP32-C3: Button + LEDbasicsbeginnerRead & run →ESP32-C3: DHT22 Temperature & HumiditysensorsbeginnerRead & run →ESP32-C3: HC-SR04 Ultrasonic DistancesensorsbeginnerRead & run →ESP32-C3: PIR Motion DetectorsensorsbeginnerRead & run →ESP32-C3: RGB LEDbasicsbeginnerRead & run →ESP32-C3: Serial HellocommunicationbeginnerRead & run →ESP32-C3: Serial EchocommunicationbeginnerRead & run →ESP32-C3: Servo Motor SweeproboticsbeginnerRead & run →ESP32: 7-Segment CounterdisplaysbeginnerRead & run →ESP32 BLE AdvertisecommunicationintermediateRead & run →ESP32 Blink LEDbasicsbeginnerRead & run →ESP32: BMP280 Weather StationsensorsintermediateRead & run →ESP32-C3 BLE AdvertisecommunicationintermediateRead & run →ESP32-C3 HTTP ServercommunicationintermediateRead & run →ESP32-C3 WiFi ConnectcommunicationbeginnerRead & run →ESP32-C3 WiFi ScancommunicationbeginnerRead & run →ESP32-CAM + ILI9341 Live PreviewdisplaysintermediateRead & run →ESP32-CAM: Webcam DemosensorsbeginnerRead & run →ESP32: DHT22 Temperature & HumiditysensorsbeginnerRead & run →ESP32 Doom — Raycaster (ILI9341)gamesadvancedRead & run →ESP32 Dual ADC ReadercircuitsbeginnerRead & run →ESP32: HC-SR04 Ultrasonic DistancesensorsbeginnerRead & run →ESP32 HTTP ServercommunicationintermediateRead & run →ESP32: Pure ESP-IDF BlinkbasicsintermediateRead & run →ESP32: Analog JoysticksensorsbeginnerRead & run →ESP32: MPU-6050 AccelerometersensorsintermediateRead & run →ESP32: SSD1306 OLED DisplaydisplaysintermediateRead & run →ESP32: SSD1306 OLED (4-pin I2C)displaysintermediateRead & run →ESP32: PIR Motion DetectorsensorsbeginnerRead & run →ESP32 LEDC PWM RGBcircuitsintermediateRead & run →ESP32 Serial EchocommunicationbeginnerRead & run →ESP32: Servo Motor + PotentiometerroboticsbeginnerRead & run →ESP32: Stepper + A4988motorsintermediateRead & run →ESP32 WiFi ConnectcommunicationbeginnerRead & run →ESP32 WiFi ScancommunicationbeginnerRead & run →

The classic starting point: digital I/O, analog reads and Serial Monitor basics on the ATmega328P.

Uno: 7-Segment CounterdisplaysbeginnerRead & run →Uno: DHT22 Temperature & HumiditysensorsbeginnerRead & run →Uno: HC-SR04 Ultrasonic DistancesensorsbeginnerRead & run →Uno: NTC Thermistor TemperaturesensorsintermediateRead & run →Arduino Uno: SSD1306 OLED (4-pin I2C)displaysintermediateRead & run →Uno: Photoresistor Light SensorsensorsbeginnerRead & run →Uno: PIR Motion DetectorsensorsbeginnerRead & run →Uno: Potentiometer → SerialsensorsbeginnerRead & run →Uno: RGB LED CyclebasicsbeginnerRead & run →Uno: Servo Motor SweeproboticsbeginnerRead & run →Arduino Uno: Stepper + A4988motorsintermediateRead & run →

Same AVR brain, different bodies — Nano for breadboards, Mega for when you run out of pins.

Mega: Blink LEDbasicsbeginnerRead & run →Mega: 8-LED ChasebasicsbeginnerRead & run →Arduino Mega 16-LED BarcircuitsbeginnerRead & run →Mega: Serial HellocommunicationbeginnerRead & run →Mega: Serial LED ControlcommunicationintermediateRead & run →Nano: Blink LEDbasicsbeginnerRead & run →Nano: Button + LEDbasicsbeginnerRead & run →Nano: PWM FadebasicsbeginnerRead & run →Arduino Nano Sensor StationcircuitsbeginnerRead & run →Nano: Serial HellocommunicationbeginnerRead & run →

Eight pins, 8 KB of flash. Small enough to force tight code.

ATtiny85: Blink LEDbasicsbeginnerRun in simulator →ATtiny85: Button + LEDbasicsbeginnerRun in simulator →ATtiny85: NTC Temperature SensorsensorsintermediateRun in simulator →ATtiny85: PWM LED FadebasicsintermediateRun in simulator →

RP2040 projects: dual-core ARM at 133 MHz, PIO, and the friendliest ADC in the lineup.

Pico: 7-Segment CounterdisplaysbeginnerRun in simulator →[Pico] ADC ReadsensorsbeginnerRun in simulator →[Pico] Blink LEDbasicsbeginnerRun in simulator →Pico: Button + LEDbasicsbeginnerRun in simulator →Pico: DHT22 Temperature & HumiditysensorsbeginnerRun in simulator →Pico Doom — Raycaster DemogamesadvancedRun in simulator →Pico: HC-SR04 Ultrasonic DistancesensorsbeginnerRun in simulator →[Pico] I2C EEPROM R/WcommunicationintermediateRun in simulator →[Pico] I2C RTC ReadcommunicationintermediateRun in simulator →[Pico] I2C ScannercommunicationintermediateRun in simulator →Pico: Analog JoysticksensorsbeginnerRun in simulator →[Pico] Multi-Protocol DemocommunicationadvancedRun in simulator →Pico: NTC Thermistor TemperaturesensorsintermediateRun in simulator →Raspberry Pi Pico: SSD1306 OLED (4-pin I2C)displaysintermediateRun in simulator →Pico: PIR Motion DetectorsensorsbeginnerRun in simulator →Pico: RGB LED CyclebasicsbeginnerRun in simulator →[Pico] Serial EchocommunicationbeginnerRun in simulator →[Pico] Serial LED ControlcommunicationbeginnerRun in simulator →Pico: Servo Motor SweeproboticsbeginnerRun in simulator →[Pico] SPI LoopbackcommunicationintermediateRun in simulator →Raspberry Pi Pico: Stepper + A4988motorsintermediateRun in simulator →

Web servers, WebSockets and relays over WiFi on the Pico W.

Pico W — Async LED control over Wi-FiRun in simulator →Pico W — IoT relay web serverRun in simulator →Pico W — Web servo controllerRun in simulator →Pico W — WebSocket-controlled LEDRun in simulator →

Blue Pill, Black Pill and friends — ARM Cortex-M boards with far more timers than an Uno.

STM32 Black Pill BlinkbasicsbeginnerRun in simulator →STM32 Black Pill (F401) BlinkbasicsbeginnerRun in simulator →STM32 Black Pill: SSD1306 OLED (I2C)displaysintermediateRun in simulator →STM32: 7-Segment CounterbasicsbeginnerRun in simulator →[STM32 + STM32] Blue Pill → Black PillcommunicationintermediateRun in simulator →STM32 Blue Pill BlinkbasicsbeginnerRun in simulator →STM32: BMP280 Weather Sensor (I2C)sensorsintermediateRun in simulator →STM32: Push Button -> LEDbasicsbeginnerRun in simulator →STM32 Blue Pill (F103CB) BlinkbasicsbeginnerRun in simulator →STM32: MPU6050 IMU (I2C)sensorsintermediateRun in simulator →STM32: SSD1306 OLED Display (I2C)displaysintermediateRun in simulator →STM32: RGB LED Color CyclebasicsbeginnerRun in simulator →STM32: DS1307 RTC Clock (I2C)sensorsintermediateRun in simulator →STM32 Serial CountercommunicationbeginnerRun in simulator →STM32: Stepper MotormotorsintermediateRun in simulator →STM32: Slide Switch -> LEDbasicsbeginnerRun in simulator →STM32: Weather Station (BMP280 + OLED)sensorsintermediateRun in simulator →[STM32 + ESP32] GPIO SynccommunicationadvancedRun in simulator →STM32F4 Discovery LED BlinkbasicsbeginnerRun in simulator →Netduino 2 Serial CountercommunicationbeginnerRun in simulator →Netduino Plus 2 BlinkbasicsbeginnerRun in simulator →STM32 Blue Pill: SSD1306 OLED (4-pin I2C)displaysintermediateRun in simulator →Olimex STM32-H405 BlinkbasicsbeginnerRun in simulator →[STM32 + Arduino] GPIO MirrorcommunicationintermediateRun in simulator →[STM32 + Arduino] Serial LinkcommunicationintermediateRun in simulator →

Full Linux on a Raspberry Pi, driving GPIO from Python.

[Pi 3] Blink an LEDbasicsbeginnerRun in simulator →[Pi 3] Running Lights (5 LEDs)basicsintermediateRun in simulator →[Pi 4] Button Toggles LEDbasicsbeginnerRun in simulator →[Pi 4] RGB LED Color CyclebasicsintermediateRun in simulator →[Pi 5] PIR Motion AlarmsensorsintermediateRun in simulator →[Pi 5] Traffic LightbasicsintermediateRun in simulator →

Two boards in one simulation — watch them talk over UART, GPIO and handshakes.

[2× Pico W] Bidirectional Digital HandshakecommunicationbeginnerRun in simulator →[2× Pico W] Digital GPIO MirrorbasicsbeginnerRun in simulator →[2× Pico W] Serial1 Passthrough (UART0)communicationintermediateRun in simulator →[Pi + Arduino] Serial LED ControlcommunicationadvancedRun in simulator →

Real SPICE simulation: dividers, filters, op-amps, rectifiers — with an oscilloscope on every node.

Common-Emitter AmplifiercircuitsadvancedRun in simulator →Capacitor Charging CurvecircuitsintermediateRun in simulator →Darlington Pair (High Current)circuitsadvancedRun in simulator →Half-Wave RectifiercircuitsintermediateRun in simulator →LED with Current-Limiting ResistorcircuitsbeginnerRun in simulator →MOSFET PWM LED DimmercircuitsintermediateRun in simulator →LED Bar GraphcircuitsbeginnerRun in simulator →NPN Transistor LED SwitchcircuitsintermediateRun in simulator →NTC Temperature SensorcircuitsbeginnerRun in simulator →Comparator with LEDcircuitsintermediateRun in simulator →Difference AmplifiercircuitsadvancedRun in simulator →Inverting Amplifier (LM358)circuitsintermediateRun in simulator →Schmitt TriggercircuitsadvancedRun in simulator →Voltage Follower (Buffer)circuitsbeginnerRun in simulator →Parallel ResistorscircuitsbeginnerRun in simulator →Photoresistor Light SensorcircuitsbeginnerRun in simulator →PNP High-Side SwitchcircuitsintermediateRun in simulator →Potentiometer ADC ReadercircuitsbeginnerRun in simulator →RC Low-Pass FiltercircuitsbeginnerRun in simulator →Reverse Polarity ProtectioncircuitsbeginnerRun in simulator →Voltage DividercircuitsbeginnerRun in simulator →Wheatstone BridgecircuitsintermediateRun in simulator →Zener Voltage RegulatorcircuitsintermediateRun in simulator →

Gates, latches, adders, motor drivers and power supplies — the glue between digital and analog.

AND Gate AlarmcircuitsbeginnerRun in simulator →Battery Voltage MonitorcircuitsbeginnerRun in simulator →4-bit Binary CountercircuitsbeginnerRun in simulator →Full Adder (1-bit)circuitsintermediateRun in simulator →DC Motor Control (L293D)circuitsintermediateRun in simulator →Motor Speed Control (PWM)circuitsintermediateRun in simulator →LM317 Adjustable PSUcircuitsintermediateRun in simulator →Logic Probe (HIGH/LOW/FLOATING)circuitsintermediateRun in simulator →Mixed: MCU + AND gate + transistor (coexistence test)circuitsintermediateRun in simulator →NAND SR LatchcircuitsintermediateRun in simulator →Optocoupler Signal IsolationcircuitsintermediateRun in simulator →7805 Regulated Power SupplycircuitsbeginnerRun in simulator →Relay-Controlled LEDcircuitsintermediateRun in simulator →XOR Toggle DetectorcircuitsbeginnerRun in simulator →

Z80 and Intel 8080 CPUs emulated instruction-for-instruction — assembly, C-compiled programs, and the 1983 Galaksija home computer.

Z80 Comet ScannerintermediatecircuitsRun in simulator →
Z80 LED Chaser in C (no board)advancedcircuitsRun in simulator →
Z80 Larson Scanner (no board)intermediatecircuitsRun in simulator →
Galaksija — 1983 Z80 home computeradvancedcircuitsRun in simulator →
Intel 8080 Banner StreameradvancedcircuitsRun in simulator →
Intel 8080 Button CounterintermediatecircuitsRun in simulator →
Kill the Bit (1975)advancedgamesRun in simulator →

49 IoT projects from the 100-days series — Blynk dashboards, Telegram alerts, web servers, sensors and robots, mostly MicroPython.

AQI ESPintermediatedisplaysRun in simulator →
Auto Night Light using LDR (ESP32 + MicroPython)beginnersensorsRun in simulator →
Battery Monitor with Blynk IoTadvancedcommunicationRun in simulator →
Bluetooth Based Wireless LED Control SystemadvancedcommunicationRun in simulator →
Blynk Based IoT Relay Control (MicroPython)advancedcommunicationRun in simulator →
Blynk Controlled DC Brushless FanadvancedcommunicationRun in simulator →
Clap Toggle Switch using ESP32 & Digital Sound Sensor (MicroPython)beginnersensorsRun in simulator →
DC Motor Speed Control (Web Slider)intermediateroboticsRun in simulator →
DHT11 Web Server using ESP32 & MicroPythonintermediatecommunicationRun in simulator →
Dimmer LED using Potentiometer (MicroPython)beginnerroboticsRun in simulator →
Dual IR Entry Exit Detector with Telegram AlertsintermediatecommunicationRun in simulator →
EEPROM Simulation using MicroPython on ESP32beginnerbasicsRun in simulator →
ESP32 BLE LED ControladvancedcommunicationRun in simulator →
ESP32 Hotspot (Access Point) Setup MicroPythonintermediatecommunicationRun in simulator →
ESP32 IR Sensor Telegram Alert (MicroPython)intermediatecommunicationRun in simulator →
ESP32 OLED Smart UI Eyes Animation Time & Weather (MicroPython)intermediatedisplaysRun in simulator →
Flask Server Based LED Control using MicroPythonintermediatecommunicationRun in simulator →
IoT Atmospheric Monitoring System using ESP32, wowki & BlynkadvancedcommunicationRun in simulator →
IoT Based DSM Smart MeteringadvancedcommunicationRun in simulator →
IoT Environment Monitoring With Anomaly DetectionintermediatecommunicationRun in simulator →
IoT Relay Control Web Server (Raspberry Pi Pico 2W)intermediatecommunicationRun in simulator →
IoT Smart Irrigation SystemadvancedcommunicationRun in simulator →
Joystick Controlled ServobeginnerroboticsRun in simulator →
Joystick Direction Display with OLEDintermediatedisplaysRun in simulator →
MicroPython WatchintermediatedisplaysRun in simulator →
MQ4 Gas Leak Detection System using ESP32 and MicroPythonbeginnerbasicsRun in simulator →
MQ7 CO Gas Detection ESP32beginnerbasicsRun in simulator →
MQ 135 Gas Sensor with ESP32 (MicroPython)advancedsensorsRun in simulator →
NTP Synchronized Digital Clock using ESP32 & MAX7219intermediatedisplaysRun in simulator →
OTA Update Pico2WadvancedcommunicationRun in simulator →
Password Lock System using ESP32intermediatedisplaysRun in simulator →
Pico 2 W Dht11 Http Csv LoggerintermediatecommunicationRun in simulator →
Pico W Async LED Control (MicroPython)intermediatecommunicationRun in simulator →
Pico W Web Servo ControlleradvancedroboticsRun in simulator →
PIR Motion Detector using Raspberry Pi Pico 2W & MicroPythonbeginnerbasicsRun in simulator →
Potentiometer VisualizerbeginnerbasicsRun in simulator →
Pulse MonitorintermediatedisplaysRun in simulator →
Raspberry Pi Pico 2 W ThingsBoard IoTintermediatecommunicationRun in simulator →
RGB Color Mixer using Potentiometers (ESP32 + MicroPython)beginnerroboticsRun in simulator →
Servo Motor Control with Raspberry Pi Pico 2 W (MicroPython)beginnerroboticsRun in simulator →
Single Digit Seven Segment Display with Raspberry Pi-Pico (MicroPython)beginnerbasicsRun in simulator →
Smart Home Automation SystemadvancedcommunicationRun in simulator →
Smart Indoor Security SystemintermediatecommunicationRun in simulator →
Smart IoT Gas Monitoring SystemintermediatecommunicationRun in simulator →
Stepper Motor Control using ESP32 & A4988 (MicroPython)intermediateroboticsRun in simulator →
Temperature Based LED Indicator (MicroPython ESP32)intermediateroboticsRun in simulator →
Ultrasonic LED Distance Indicator ESP32 MicroPythonbeginnersensorsRun in simulator →
WebSocket LED Control using Raspberry Pi Pico WadvancedcommunicationRun in simulator →
Wi Fi Controlled 4WD Robot CarintermediateroboticsRun in simulator →