IRR BlocksIoT & Robotics Rwanda
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Wire and Blink an LED

Build a real-looking UNO R3, breadboard, 330 Ω resistor and LED circuit, then program it to blink three times.

Wire and Blink an LED

Objectives

  • Explain how breadboard strips connect component legs.
  • Wire a digital pin through a 330 Ω resistor to the LED anode and return the cathode to GND.
  • Run a program that turns the LED on for one second and off for one second, three times.

Expected behavior

The LED turns on for 1 second and off for 1 second, three times, then the program finishes.

What this simulation can and cannot show

Teaching model: a simulated UNO R3 with ideal connections. It checks wiring rules and observes block execution; it does not solve electrical currents, compile or flash a real board. Real boards and parts differ — check them before building.

Choose how to start

Start blank to place every part yourself, or load the starter: board, breadboard, resistor, LED and an unbound blink program. You still insert parts, make each connection and bind the blocks.

Build steps

0 / 10 steps complete

  1. Place the UNO R3 board (Not yet)

    The board's pins can switch between HIGH and LOW. It also provides GND, the return path.

  2. Place the breadboard (Not yet)

    Holes in the same short strip of five are connected inside the breadboard. Different strips are separate.

  3. Insert the 330 Ω resistor (Not yet)

    Put each resistor leg in a different strip, so current must pass through the resistor. It limits the LED current.

  4. Insert the LED (Not yet)

    Put the LED legs in two different strips. The longer leg is the anode (+); the shorter leg is the cathode (−).

  5. Connect a digital pin to the resistor (Not yet)

    Run a wire from a digital pin such as D13 to the resistor's strip. Any free digital output pin works.

  6. Connect the resistor to the LED anode (Not yet)

    The resistor's other leg must share a strip (or a wire) with the LED's long leg.

  7. Return the LED cathode to GND (Not yet)

    Without a return path to GND, no current can flow and the LED stays dark.

  8. Build the blink program (Not yet)

    Use LED ON, wait 1 second, LED OFF, wait 1 second, repeated 3 times. Both waits matter.

  9. Bind every LED block to your LED (Not yet)

    Bindings tell each block which component to control. The pin comes from your wiring.

  10. Run and observe three cycles (Not yet)

    Completion is awarded only after the simulation observes three ON/OFF cycles with both one-second waits on a valid circuit.

Lesson check

Run the circuit when every build step is done. Completion needs three observed ON/OFF cycles with both one-second waits.

Cycles observed: 0 of 3

Completion is saved only in this browser. It is not synced to an account and is not a certificate.

Open the Code tab to read the generated C++: both delay(1000) waits appear inside the repeat loop. It is not compiled or flashed.

Hints
  • Select a part, choose a leg, pick a hole and press “Attach to hole” to insert it into the breadboard.
  • If the LED shows “Disconnected”, open the wiring explanations: they name the missing return, resistor or reversed leg.
  • If the run finishes but the lesson is not complete, check that both waits are exactly 1 second and the loop repeats 3 times.

Draft lesson and translations — fluent educator review pending.

Board inspector

This project has no board yet.

Add a supported board to check wiring, simulate and preview code. Physical compatibility is unverified.

Lessons keep their board. Use a free project to try another board.

Wiring checks

Limited virtual teaching rules — not physical safety certification or a general electrical solver. Passing wiring checks does not run code or award completion.

Draft explanations and translations — fluent educator review pending.

Wiring checks blocked

Error: 0 · Warning: 0 · Unsupported: 1

  • Unsupported · missing-board

    This draft has no programmable board.

    Repair hint: Add a supported board and connect its named terminals explicitly.

    Involved IDs

    Parts tray

    Planned boards and parts

    Shown for planning only. They cannot be added, simulated or exported yet.

    • Raspberry Pi Pico W · RP2040 · Not available yet · Planned gate C
    • Raspberry Pi Pico 2 · RP2350 · Not available yet · Planned gate C
    • Raspberry Pi 4 Model B · other RAM sizes and PCB revisions · Not available yet · Planned gate D
    • BeagleBone Black Wireless · Not available yet · Planned gate D
    • Analog temperature and water-level circuit inputs · Not available yet · Planned gate C
    • Motors, servos, other displays and SPI/UART bus modules · Not available yet · Planned gate C

    Terminal inspector

    None

    Connections

    Use these labelled controls instead of dragging or selecting small terminals. Wires cross without joining.

    No wires yet.

    Select a part, then drag it or use arrow keys to move it. In Wire mode, choose two terminals. Visual overlap never creates electrical contact; use the attachment form to occupy a breadboard hole.

    Limited circuit simulation for the published UNO R3 and ESP32-DevKitC V4 teaching profiles. Code view offers qualified C++ and JavaScript previews (plus MicroPython for ESP32) with wiring manifests, plus document JSON. No CPU, Wi-Fi or Bluetooth is simulated, and physical compatibility is unverified.

    Draft learning copy and translations — fluent educator review is still required.

    Guest circuit projects

    Saved on this browser. Nothing uploads automatically; a signed-in adult or educator can press Save to cloud for a private copy. Download a copy before clearing browser data.

    Local save pending

    Draft explanations and en/rw/fr translations need fluent educator review.