The default I2C address is 0x40.

Power Pins

• VIN - this is the power pin. It can be powered by 3V or 5V. 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's 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's 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 connect to development boards with STEMMA QT (Qwiic) connectors or to other things with various associated accessories.

Input Pins

The pins are in a low side measurement configuration by default. They are available along the bottom edge of the board and the terminal block on the top edge of the board.

• VIN+ - Positive input pin.
• VIN- - Negative input pin.
• VBUS - Bus voltage input pin.

To measure low-side, Connect VIN- to ground and VIN+ to your load's lowest potential. VBUS should connect to the highest project voltage, up to 85V.

To measure high-side, connect VIN+ to VBUS to the highest project voltage, and VIN- to the load's highest potential.

VBUS Jumper

On the back of the board, above the VIN+ and VBUS pins, is the VBUS jumper. This jumper connects or disconnects VBUS from VIN+. When the jumper is open (default), it configures the board for low side measurement. When the jumper is soldered closed, it configures the board for high side measurement. 

Interrupt Pin

• ALRT - The alert/interrupt pin. The default state is active low.

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.

Address Jumpers

On the back of the board are two address jumpers, labeled A0 and A1, above the Addr label on the board silk. These jumpers allow you to chain up to 4 of these boards on the same pair of I2C clock and data pins. To do so, you solder the jumpers "closed" by connecting the two pads.

The default I2C address is 0x40. The other address options can be calculated by “adding” the A0/A1 to the base of 0x40.

A0 sets the lowest bit with a value of 1 and A1 sets the next bit with a value of 2. The final address is 0x40 + A1 + A0 which would be 0x43.


So for example if A1 is soldered closed and A0 is soldered closed, the address is 0x40 + 2 + 1 = 0x43.

If only A0 is soldered closed, the address is 0x40 + 1 = 0x41

If only A1 is soldered closed, the address is 0x40 + 2 = 0x42

The table below shows all possible addresses, and whether the pin(s) should be high (closed) or low (open).