This AVR tutorial will discuss interfacing Light Emitting Diodes with Atmel's AVR series of Microcontrollers. A LED is an acronym for Light Emitting Diode and is basically a electronic device which emits light when an electric current flows through it. The electronic symbol for a LED is : LED Symbol


General purpose LEDs used in digital circuits require around 75mA or less and so we usually use resistors to limit the current flowing through the LED when it is connected within a circuit as shown below. The resistance of the resistor is calculated using the well known formula V=IR.