Drawing to a Small TFT Display: the ILI9341 and STM32 - JohnHau/mis GitHub Wiki

As you learn about more of your microcontroller’s peripherals and start to work with more types of sensors and actuators, you will probably want to add small displays to your projects. Previously, I wrote about creating a simple program to draw data to an SSD1331 OLED display, but while they look great, the small size and low resolution can be limiting. Fortunately, the larger (and slightly cheaper) ILI9341 TFT display module uses a nearly-identical SPI communication protocol, so this tutorial will build on that previous post by going over how to draw to a 2.2″ ILI9341 module using the STM32’s hardware SPI peripheral.

We’ll cover the basic steps of setting up the required GPIO pins, initializing the SPI peripheral, starting the display, and then finally drawing pixel colors to it. This tutorial won’t read any data from the display, so we can use the hardware peripheral’s MISO pin for other purposes and leave the TFT’s MISO pin disconnected. And as with my previous STM32 posts, example code will be provided for both the STM32F031K6 and STM32L031K6 ‘Nucleo’ boards.

Step 0: RCC Setup As with most STM32 projects, the first thing we should do is enable the peripherals that we will use. In this case, that’s just GPIOA, GPIOB, and SPI1. As in previous STM32 posts, I will use the device header files provided by ST for basic peripheral variable definitions, and determine the target chip from definitions passed in from the Makefile:

Programming the Display When the ILI9341 first powers on it should show a uniform bright white color, but that’s just the backlight LEDs. The display will not try to show anything at all until it is initialized. Be aware that a broken display might still show a bright white screen when power is applied, but these modules are fairly sturdy. I’ve gone so far as to pry them apart and remove the backlights, and the panels worked even after being bluntly removed from the case.