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 − − + + − − + + 1 1 5 5 10 10 15 15 20 20 25 25 30 30 j j i i h h g g f f e e d d c c b b a a BMP280 VCC GND SCL SDA U2 · BMP280 U1 · Arduino UNO U1 · Arduino UNO U2 · BMP280 2 2 4 4 6 6 8 8 10 10 11 11 12 12 13 13 f f g g h h MODEL · DC simulation USB 46.3 mA VCC 325 µA 0 V 3.3 V 3.67 V 3.67 V 3.3 V 0 V 3.67 V 3.67 V 0 V