The default I2C address is 0x18.

Power Pins

• VIN - this is the power pin. 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'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.

1-Wire Header Pins

At the top edge of the board are 8 1x3 header pins. These pins let you connect 8 different 1-wire sensors to the breakout board. Each set of 3 pins (+, 1W and -) are labeled 0-7. These labels denote the channel number that you'll use in the code.

• + - the power connection for the 1-wire sensor. It shares the same voltage level as VIN.
• 1W - the signal connection for the 1-wire line
• - - the ground connection for the 1-wire sensor

Address Pins

On the back of the board are three address jumpers, labeled A0, A1, and A2. These jumpers allow you to chain up to 8 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.

On the front of the board are two address pins, labeled A0 and A1. Just like the jumpers, these pins allow you to change the I2C address to connect multiple boards by connecting them to VIN. There is no broken out pin for A2.

The default I2C address is 0x18. The other address options can be calculated by "adding" the A0/A1/A2 to the base of 0x18.

A0 sets the lowest bit with a value of 1, A1 sets the next bit with a value of 2 and A2 sets the next bit with a value of 4. The final address is 0x18 + A2 + A1 + A0 which would be 0x1F.

So for example if A2 is soldered closed and A0 is soldered closed, the address is 0x18 + 4 + 1 = 0x1D.


If only A0 is soldered closed, the address is 0x18 + 1 = 0x19


If only A1 is soldered closed, the address is 0x18 + 2 = 0x1A


If only A2 is soldered closed, the address is 0x18 + 4 = 0x1C

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

Power LED and Jumper

• Power LED - on the left side of the board, above the STEMMA QT connector, is the power LED, labeled on. It is the green LED.
• LED jumper - on the back of the board is a jumper for the power LED. It is labeled LED on the board silk. If you want to disable the power LED, cut the trace on this jumper.