PORT3 PORT4 ANALOG_IN PWM PORT0 PORT1 PORT2 0 Rx Tx 7 8 15 16 23 24 31 32 39 0 7 0 5 49 50 RX TX 1 6 ISP 48 L VCC VCC VCC GND GND VIN GND GND GND AREF wiring.org.co Rx Tx SCL SDA USB EXT 1 2 3 PWR