3.0 - Blink

Building on our Blink skillz, lets build a LED circuit and control it with UNO!

For this project you will need a breadboard, some jumper wires, a 220 or 330 ohm resistor, and an LED.

led

Know your LED: the longer leg is the anode and connects to positive voltage, i.e. + or 5V; the short leg is the cathode and connects to ground, i.e. - or GND.

Know your resistor: resistors are marked by color bands, but they are often hard to read - check them with a multimeter.

3.1 - First circuit

  1. Gently push the legs of your LED into two different rows on the breadboard. Remember which one is the long leg!

    led

  2. Connect the LED cathode (short leg) to GND by inserting the legs of a 220 ohm resistor into the row and the - Rail.

    led

  3. Connect the LED anode (long leg) to 5V by inserting a jumper wire into the row and the + Rail.

    led

  4. Connect the breadboard to the UNO’s power supply:
    • use a red jumper wire to connect the + rail to the pin labeled 5V on the UNO.
    • use a black jumper wire to connect the - rail to any pin labeled GND on the UNO (you have 3 choices).

    led

    led

  5. Plug your UNO into your usb cable.

You should now have a beautiful glowing LED!

3.2 - Blink it!

This circuit is drawing power from UNO, but it is not controlled by it. We need to connect the LED to a pin so we can start blinking!

  1. Unplug the wire connecting the anode from the + rail.

  2. Connect the anode wire to pin 10 on the UNO.

    led

    led

  3. On the IDE Blink sketch, replace LED_BUILTIN with 10. The basic code should look like:

    void setup() {
    pinMode(10, OUTPUT);
}

void loop() {
    digitalWrite(10, HIGH);
    delay(1000);
    digitalWrite(10, LOW);
    delay(1000);
}

  4. Plug UNO into the usb, and click the upload arrow to load the sketch.

You should now have a beautiful Blinking LED!

3.3 - Extra credit