The default I2C address is 0x48.

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.
  
• REF - this is the positive reference pin. By default this is connected to VIN.
• GND - common ground for power and logic.
• COM - this is the negative reference pin. By default this is connected to GND.

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

• A0-A7 - The 8 inputs to the ADC. These inputs can get up to 70 Ksamples per second (you'll need 3.4MHz I2C speed support for max speed rate), and 8-bits of resolution. They're ideal for adding a ton of potentiometers or flex sensors to a build.

Address Pins

On the back of the board are two address jumpers, labeled AD0 and AD1. 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.

On the front of the board are two address pins, labeled AD0 and AD1. Just like the jumpers, these pins allow you to change the I2C address to connect multiple boards by connecting them to VIN.

The default I2C address is 0x48. The other address options can be calculated by “adding” the AD0/AD1 to the base of 0x48.

AD0 sets the lowest bit with a value of 1 and AD1 sets the next bit with a value of 2. The final address is 0x48 + AD1 + AD0 which would be 0x4B.

If only AD0 is soldered closed, the address is 0x48 + 1 = 0x49

If only AD1 is soldered closed, the address is 0x48 + 2 = 0x4A

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

Reference Jumpers

• Ext Ref - On the back of the board, directly below the board label on the silk, is the external reference jumper. Cut this jumper to change the reference voltage. The new external reference voltage must be less than the power supply connected to the board.
• Ext Com - On the back of the board, below the Ext Ref jumper, is the external negative/common reference jumper. Cut this jumper to change the negative reference.

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 the green LED.
• LED jumper - In the upper right corner on the back of the board is a jumper for the power LED. If you wish to disable the power LED, simply cut the trace on this jumper.