The default I2C address is 0x3A.

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.
• 3Vo - this is the 3.3V output from the voltage regulator, you can grab up to 100mA from this if you like.
• 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.

Address Pin and Jumper

You can change the I2C address with either the ADDR pin on the front of the board or the address jumper on the back of the board, labeled A0 on the board silk.

This pin lets you to chain up to 2 of these boards together on the same pair of I2C clock and data pins. To do so, you solder the jumper "closed" by connecting the two pads or connect the ADDR pin to VIN. The default I2C address is 0x3A. The other address options can be calculated by “adding” the value of ADDR/A0 to the base of 0x3A.

A0 sets the lowest bit with a value of 1. The final address is 0x3A + A0 which would be 0x3B.

If A0 is soldered closed or ADDR is connected to VIN, the address is 0x3A + 1 = 0x3B

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

Power LED and Jumper

• 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 a green LED.
• LED jumper - This jumper is located on the back of the board and is labeled LED on the board silk. Cut the trace on this jumper to cut power to the "on" LED.