• GND - this is the power and signal ground pin
• Vin - this is the power pin, connect to 3-5VDC - it has reverse polarity protection but try to wire it right!
• 3Vo - this is the 3.3V output from the onboard regulator, you can 'borrow' about 100mA if you need to power some other 3.3V logic devices

• The display comes with two STEMMA QT ports. These connectors allow you to connect to development boards with STEMMA QT connectors or to other things with various associated accessories. Since they are connected in parallel, either side can be used as an input or output. They can be used to daisychain multiple STEMMA QT breakouts.

• Clk - this is the Clock pin. Connect to I2C SCL
• Data - this is the Data pin. Connect to I2C SDA

• CS - this is the Chip Select pin, it is used by SPI to select the device.
• DC - this is the Data/Command selector pin used to differentiate between Data and Commands that are sent to the display.
• Clk - this is the Clock pin. Connect to SPI SCLK
• Data - this is the Data pin. Connect to SPI MOSI

You'll notice there are two open jumpers on the back towards the center of the board.

• To use in I2C mode, you'll want to make sure the J1 jumper is open. To use in SPI mode, you'll want to bridge the J1 jumper. The board comes in I2C mode by default.
• The A0 jumper is used for setting the I2C address. When it is open, the I2C address is 0x3D. When it is bridged, the I2C Address is 0x3C. Alternatively, by tying the A0 pin to ground, you can set the I2C address to 0x3C.

• Above the "on" LED on the left side of the back of the board is a closed jumper. If you want to disable the power LED, you can cut the trace here. After cutting the trace, if you wish to enable it again, you can solder the jumper closed.

• Rst - this is the Reset pin, you may be able to share this with your microcontroller reset pin but if you can, connect it to a digital pin.