The default I2C address is 0x68.

Power Pins

• VIN - this is the power pin. Since the ADC chip uses 3-5 VDC to power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V.
• GND - common ground for power and logic.

I2C Logic Pins

• SCL - I2C clock pin, connect to your microcontroller I2C clock line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
• SDA - I2C data pin, connect to your microcontroller I2C data line. This pin can use 3-5V logic, and there's a 10K pullup on this pin.
• STEMMA QT - These connectors allow you to connectors to dev boards with STEMMA QT connectors or to other things with various associated accessories

ADC Inputs

The MCP3421 has two inputs: V+ and V-. V+ is the positive input and V- is the negative input. The inputs are available via the terminal block at the top of the board or the two pins labeled V+ and V- at the bottom of the board.

The MCP3421 is set up for differential inputs, which means that you can read positive or negative differences between the two inputs, as long as both signals are between 0 and 2.048V.

Power LED

• Power LED - In the upper left corner, above the STEMMA connector, on the front of the board, is the power LED, labeled on. It is the green LED.