Stuck? Check the circuit first

Check the circuit

1. The USB cable is plugged into the board and the computer, and the board’s power light is on.
2. The Arduino IDE has “Arduino Uno” and the right port selected.
3. Every part shares the board’s GND.
4. Every part faces the right way round.
5. Each wire goes to the pin the sketch uses.
6. No jumper is loose. Press each one in.
7. Anything that draws current has its resistor. Each UNO R3 I/O pin is rated for 20 mA DC².

Then check the code

1. The pin number in the sketch matches the wire.
2. pinMode() sets each output pin to OUTPUT.
3. The Serial Monitor’s speed matches the number in Serial.begin().

Back to the lessons

Sources

1. Booth et al., CHI 2016: 20 end-⁠user developers building Arduino circuits
2. Arduino UNO R3 technical specifications: DC Current per I/O Pin: 20 mA