Power Pins: Vin - this is the power pin. The chip can use 2.5-5VDC for power. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like for Arduino, use 5V. For a 3.3V controller like a Raspbery Pi, connect to 3.3V GND - common ground for power and logic I2C Logic pins: SCL - I2C clock pin, connect to your microcontrollers I2C clock line. This pin has a 10K pullup resistor to Vin SDA - I2C data pin, connect to your microcontrollers I2C data line. This pin has a 10K pullup resistor to Vin Other Pins: ADR - This is the I2C address selection pin. This pin has a 10K pull down resistor to make the default I2C address 0x44. You can tie this pin to Vin to make the address 0x45 RST - Hardware reset pint. Has a 10K pullup on it to make the chip active by default. Connect to ground to do a hardware reset! ALR - Alert/Interrupt output. You can set up the sensor to alert you when an event has occured. Check the datasheet for how you can set up the alerts.