The MEGA-1284P Xplained has four LEDs mounted onboard, which is connected to the Atmel ATmega1284P. This is four standard yellow LEDs. The four yellow LEDs are active low.

LED0, LED2 and LED3 are shared with the 3 switches (SW0:2). When turning the LED on, set the IO pin to output low. When turning the LED off, set the IO pin as input with pull-up. The protection circuitry added to the button will make the LED shine brighter when the button is pressed and the LED is turned on. When the LED is off, any button press will light up the LED.

One dual LED is mounted near the USB connector. This is the power and status LED which is connected to the boardcontroller. This LED will be green when power is applied and will toggle between green and orange when communication over USB is ongoing.