We have example code ready to go for use with these TFTs. It's written for Arduino, which should be portable to any microcontroller by adapting the C++ source.
Two libraries need to be downloaded and installed: the TFTLCD library and the GFX library. You can install these libraries through the Arduino library manager.
Open up the Arduino library manager:
Search for the Adafruit GFX library and install it
Search for the Adafruit TFTLCD library and install it
If using an older version of the Arduino IDE (pre-1.8.10), also locate and install the Adafruit_BusIO library (newer versions do this automatically when using the Arduino Library Manager).
We also have a great tutorial on Arduino library installation at:
In the TFTLCD Library folder, you will need to edit TFTLCD.h. On about line 12, you will see "#define USE_ADAFRUIT_SHIELD_PINOUT". Comment out this line and save the file.
After restarting the Arduino software, you should see a new example folder called Adafruit_TFTLCD and inside, an example called graphicstest. Upload that sketch to your Arduino. You may need to press the Reset button to reset the arduino and TFT. You should see a collection of graphical tests draw out on the TFT.