The mini PiTFT connects to the 'top' 2x12 headers on the Pi's 2x20 header connection. It uses the following pins:

• 5.0V - Connected to the display backlight
• 3.3V - Connected to the display power and also the STEMMA QT / Qwiic connector
• GND - Ground for everything
• SDA & SCL - I2C data for the STEMMA QT / Qwiic connector. Not used by buttons or display
• GPIO22 - Used to turn the backlight on and off. If you never want to turn the backlight off, cut the small jumper on the bottom of the PiTFT to free up GPIO22
• GPIO23 & GPIO24 - Connected to the two front buttons. These pins have 10K pullups to 3.3V so when the button is pressed, you will read a LOW voltage on these pins
• SCK, MOSI, CE0 & GPIO25 - These are the display control pins. Note that MISO is not connected even though it is a SPI pin because you cannot read back from the display.

Not used: GPIO4, GPIO17, GPIO18, GPIO27

If you are using the 240x135 1.14" (small rectangular) Mini PiTFT, you can attach other hardware to the Pi on those pins if you use a stacking header - it will go through the 2x12 connector on the Mini PiTFT. This wont work on the 1.3" because the holes don't go through the PCB