SCL SDA AREF GND 13 12 ~11 ~10 ~9 8 7 ~6 ~5 4 ~3 2 1 0 IOREF RESET 3.3V 5V GND GND VIN A0 A1 A2 A3 A4 A5 DIGITAL (PWM ~) POWER ANALOG IN UNO CH340G ATMEGA328P − − GND + + − − + + 1 1 5 5 10 10 15 15 20 20 25 25 30 30 35 35 40 40 45 45 50 50 55 55 60 60 j j i i h h g g f f e e d d c c b b a a R1 · 330 Ω D1 · green A1 · Arduino UNO A1 · Arduino UNO R1 · 330 Ω D1 · green 20 20 26 26 27 27 28 28 f f i i j j GND MODEL · DC simulation USB 52.8 mA 7.98 mA 7.98 mA 4.67 V 0 V 2.03 V 0 V