If you feel the board or a component is hot or you smell smoke when you are using Arduino, immediately unplug the power and report to your lab instructor!!!
Although the Arduino uses a relatively low voltage, you can ruin your small components, individual pins, or the entire Arduino by setting up your circuit incorrectly. In rare cases, plugging in a badly wired circuit to your computer via USB could even damage the motherboard on your PC. All of these mistake ultimately come down some version of connecting a high voltage directly to a low voltage without a resistor.
- Connecting VIN or 5V directly to GND. This probably seems obvious, but you should not create a short circuit. Usually students do this unintentionally by placing a component like an LED or transistor into a circuit. It looks like it is not directly connected but the effect is the same. These components have very low resistance. You must include a resistor (or potentiometer) in any circuit that you put together.
- Connecting an I/O pin directly to GND. Just like the 5V pin, when an I/O pin is set to high and connected to ground, you have a short circuit. Aside from neglecting to include a resistor, you might misunderstand how components plugged into the bread board are connected. Read Breadboard page if you haven’t used a breadboard before.
- Connecting an I/O pin to another I/O pin. If at any point, one pin is set to high while the connected pin is set to low, you have effectively shorted a high voltage to a low voltage and will draw current above the Arduino’s maximum of 40mA.
- Apply a voltage greater than 5.5V to an I/O pin. The Arduino has some protective circuitry to handle higher voltage for short-durations. However, it will burn out the circuitry if high voltages are applied for a long period of time. Be careful with your power supply and VIN pin!
- Connecting power supply in reverse. If you are not using the USB power or barrel jack, you can use VIN to power the Arduino. You must ensure that the + supply connects to VIN and – supply goes to ground. There is no reverse voltage protection. You will burn out the main microcontroller chip and the voltage regulator.
- Applying >5V to the 5V connector pin. This is the biggest danger to your personal computer. Much like the power supply there is not reverse voltage protection. You will definitely burn our the microcontroller chip and the voltage regulator. In addition, this excessive voltage could cause current to flow backwards to your PCs USB port. You will lose your port and possibly your motherboard.
What can you do to avoid these mistakes?
- Many of these mistakes could be avoided by confirming that the Arduino pins being used are not connected to GND.
- The connectivity setting on your multimeter can tell you if you have a wire directly connecting these.
- The multimeter won’t alert you if you have a diode or transistor connecting them. Check that each of these components has a resistor associated with it.
- Knowing each pin function is essential to making sure things work the way you want them to. If you need help of pin function, read Arduino board page