Hardware Reference

In-Depth Information

Ohm's Law states that voltage is equal to the current multiplied by the resistance, or
V =

IR
. Subtracting 2.2V from 3.3V of our supply voltage, and dividing the resulting value by

.020 Amps gives 55 Ohms. 55 Ohms isn't a standard value, but 56 is, so you can use this.

But, you can always use a higher resistance value, and the LED will just be less bright.

The resistor used in this project had a value of 100 Ohms.