How to Use TFT LCD display: Examples, Pinouts, and Specs

The TFT LCD Display (Manufacturer: GMT 020-02-8P, Part ID: ST7789) is a high-performance Thin-Film Transistor Liquid Crystal Display designed for vibrant color rendering and high-resolution output. This display leverages thin-film transistor technology to deliver superior image quality, faster response times, and enhanced viewing angles. It is widely used in applications such as smartphones, tablets, handheld devices, and embedded systems.

• Portable devices like smartphones and smartwatches
• Embedded systems and microcontroller projects
• Industrial control panels
• Consumer electronics such as digital cameras and media players
• DIY electronics and prototyping with platforms like Arduino and Raspberry Pi

The TFT LCD display has an 8-pin interface. Below is the pinout description:

To use the TFT LCD display with an Arduino UNO, follow these steps:

1. Wiring the Display:

   • Connect the GND pin of the display to the GND pin of the Arduino.
   • Connect the VCC pin of the display to the 3.3V pin of the Arduino.
   • Connect the SCL pin to Arduino pin D13 (SPI Clock).
   • Connect the SDA pin to Arduino pin D11 (SPI MOSI).
   • Connect the RES pin to Arduino pin D8.
   • Connect the DC pin to Arduino pin D9.
   • Connect the CS pin to Arduino pin D10.
   • Optionally, connect the BLK pin to 3.3V or a PWM pin for backlight control.

2. Install Required Libraries:

   • Install the Adafruit_GFX and Adafruit_ST7789 libraries from the Arduino Library Manager.

3. Example Code: Use the following code to initialize and display basic graphics on the TFT LCD:

   // Include necessary libraries
   #include <Adafruit_GFX.h>       // Graphics library for rendering shapes/text
   #include <Adafruit_ST7789.h>   // Driver for ST7789 TFT LCD
   
   // Define pin connections
   #define TFT_CS    10  // Chip Select pin
   #define TFT_RST   8   // Reset pin
   #define TFT_DC    9   // Data/Command pin
   
   // Initialize the display object
   Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);
   
   void setup() {
     // Initialize the display
     tft.init(240, 240);  // Initialize with 240x240 resolution
     tft.setRotation(1);  // Set display orientation (0-3)
   
     // Fill the screen with a color
     tft.fillScreen(ST77XX_BLACK);
   
     // Draw a rectangle
     tft.fillRect(50, 50, 100, 100, ST77XX_RED);
   
     // Display text
     tft.setTextColor(ST77XX_WHITE);
     tft.setTextSize(2);
     tft.setCursor(10, 200);
     tft.print("Hello, TFT!");
   }
   
   void loop() {
     // No actions in the loop
   }
   

• Voltage Levels: Ensure the display operates at 3.3V. Using 5V may damage the module.
• Backlight Control: The backlight pin (BLK) can be connected to a PWM pin for brightness control.
• SPI Speed: Use a suitable SPI clock speed (e.g., 4 MHz) to ensure stable communication.
• Reset Pin: Always connect the reset pin (RES) to avoid initialization issues.

1. Display Not Turning On:

   • Verify the power connections (GND and VCC).
   • Ensure the backlight pin (BLK) is connected to 3.3V or a PWM pin.

2. No Output on the Screen:

   • Check the SPI connections (SCL, SDA, CS, DC).
   • Ensure the correct pins are defined in the code.
   • Verify that the Adafruit_GFX and Adafruit_ST7789 libraries are installed.

3. Flickering or Unstable Display:

   • Reduce the SPI clock speed in the library settings.
   • Ensure proper grounding between the Arduino and the display.

4. Incorrect Colors or Orientation:

   • Use the setRotation() function to adjust the display orientation.
   • Verify the color format used in the code (RGB565).

Q1: Can I use this display with a 5V microcontroller?
A1: Yes, but you must use a level shifter to convert 5V signals to 3.3V to avoid damaging the display.

Q2: How do I control the brightness of the backlight?
A2: Connect the BLK pin to a PWM-capable pin on your microcontroller and use PWM signals to adjust brightness.

Q3: Can I use this display with platforms other than Arduino?
A3: Yes, the display can be used with other platforms like Raspberry Pi or ESP32, provided they support SPI communication.

Q4: What is the maximum SPI clock speed supported?
A4: The ST7789 controller typically supports SPI clock speeds up to 15 MHz, but lower speeds (e.g., 4 MHz) are recommended for stability.

By following this documentation, you can effectively integrate and use the TFT LCD display in your projects.