We have a library with example code ready to go for use with these TFTs. The library is not incredibly fast and optimized but its a good start and can easily be ported to other micrcontrollers. However, we'll assume you're using an Arduino.
Our github repository contains all the code and examples you'll need for driving the TFT.
You'll need a few libraries to use this display
From within the Arduino IDE, open up the Library Manager...
We have example code ready to go for use with these TFTs.
Two libraries need to be downloaded and installed: first is the Adafruit ILI9341 library (this contains the low-level code specific to this device), and second is the Adafruit GFX Library (which handles graphics operations common to many displays we carry). If you have Adafruit_GFX already, make sure its the most recent version since we've made updates for better performance
Search for ILI9341 and install the Adafruit ILI9341 library that pops up!
For more details, especially for first-time library installers, check out our great tutorial at http://learn.adafruit.com/adafruit-all-about-arduino-libraries-install-use
Next up, search for Adafruit GFX and locate the core library. A lot of libraries may pop up because we reference it in the description so just make sure you see Adafruit GFX Library in bold at the top.
If using an older version of the Arduino IDE (pre-1.8.10), repeat this process one more time, looking for the Adafruit_BusIO library. Install that one too.