External Interrupts: 3 (interrupt 0), 2 (interrupt 1), 0 (interrupt 2), 1 (interrupt 3) and 7 (interrupt 4).Support TWI communication using the Wire library. Note that on the Leonardo, the Serial class refers to USB (CDC) communication for TTL serial on pins 0 and 1, use the Serial1 class. Used to receive (RX) and transmit (TX) TTL serial data using the ATmega32U4 hardware serial capability. In addition, some pins have specialized functions: Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kOhms. This is 5V on the Leonardo.Įach of the 20 digital i/o pins on the Leonardo can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. The voltage at which the i/o pins of the board are operating (i.e. A 3.3 volt supply generated by the on-board regulator. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply.
The regulated power supply used to power the microcontroller and other components on the board. You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. The power source is selected automatically.Įxternal (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The Arduino Leonardo can be powered via the micro USB connection or with an external power supply.