SeriesSearchFull courseOur workAbout & contact
// FREE MINI-COURSE · LED

LED Series

LED & Arduino from Zero — From what an LED is to controlling it with code, one 20-second lesson at a time.

11 of 12 lessons out · next: millis() vs delay(): blink without freezing

▶ Start lesson 1
  1. 01 What actually happens when you turn ON an LED?Voltage pushes current through the LED's P-N junction; electrons meeting holes release light. EP.01 · 24 s
  2. 02 Why does an LED burn without a resistor?Above ~2 V an LED's current shoots up; a resistor limits it: R = (5 V − 2 V) ÷ current. EP.02 · 20 s
  3. 03 5 lines of C++ → a real LED turns ONsetup() runs once, loop() runs forever; pinMode + digitalWrite(HIGH) puts 5 V on a pin. EP.03 · 20 s
  4. 04 Make it BLINKdelay() pauses the program; ON-wait-OFF-wait inside loop() makes a blink, and a smaller delay blinks faster. EP.05 · 20 s
  5. 05 Make it FADE (PWM)analogWrite(pin, 0–255) on a ~ pin switches very fast (PWM); a for loop raises brightness step by step. EP.06 · 20 s
  6. 06 Control it with a BUTTONINPUT_PULLUP keeps the pin HIGH until the button pulls it to GND (LOW); one if/else switches the LED. EP.10 · 20 s
  7. 07 Make it a TOGGLEOne press ON, next press OFF: remember a state in a variable and detect the press. EP.11 · 20 s
  8. 08 Traffic light with 3 LEDsThree LEDs on three pins, each with its own 220 Ω resistor: switch them ON → WAIT → OFF in turn to make a traffic light. EP.12 · 20 s
  9. 09 LED chaser (running light)Put 6 pins in an array (int leds[] = {7, 6, 5, 4, 3, 2}) and use one for loop so leds[i] lights each LED in turn; counting starts at 0. EP.18 · 20 s
  10. 10 Speed knob: potentiometer + analogReadA potentiometer (5V, wiper → A0, GND) gives 0–5 V; analogRead(A0) turns it into 0–1023, and delay(knob / 4 + 20) makes the chaser 20–275 ms per LED. EP.22 · 20 s
  11. 11 Serial.print: see your knob's numberSerial.begin + Serial.println(knob) prints the analogRead value to the Serial Monitor on your laptop. EP.61 · 24 s