How to Use 3.5 In TFT Display Module: Examples, Pinouts, and Specs

The 3.5 In TFT Display Module (Manufacturer Part ID: 3.5TFT-03-SPI-16P-8P-St7769_LCM) is a high-resolution, full-color thin-film transistor (TFT) display designed for use in embedded systems and portable devices. Manufactured by Estar Dyn, this module is equipped with the ST7769 display driver IC, which supports SPI communication for efficient data transfer. Its compact size and vibrant display make it ideal for applications requiring graphical user interfaces, such as handheld devices, industrial control panels, and IoT projects.

• Portable devices (e.g., handheld consoles, smart gadgets)
• Embedded systems with graphical user interfaces
• Industrial control panels and instrumentation
• IoT devices with visual feedback
• Educational and prototyping projects with microcontrollers (e.g., Arduino, Raspberry Pi)

The module has two connectors: a 16-pin interface for the main display signals and an 8-pin interface for the backlight and power.

1. Power Supply: Connect the VCC pin to a 3.3V power source and GND to ground.
2. Backlight: Connect LED+ and LED- to a 3.0V to 3.6V power source for the backlight. Use a current-limiting resistor if necessary.
3. SPI Communication:
   • Connect the SPI pins (CS, RESET, DC, SDI, SCK) to the corresponding pins on your microcontroller.
   • Ensure the microcontroller operates at 3.3V logic levels or use level shifters if operating at 5V.
4. Initialization: Use the ST7769 driver library or write initialization code to configure the display.

• Voltage Levels: Ensure all input signals are within the 3.3V range to avoid damage.
• Backlight Current: Use a resistor to limit the backlight current if your power source exceeds the recommended range.
• SPI Speed: Configure the SPI clock speed to match the display's requirements for stable communication.
• Reset Signal: Always initialize the display with a reset signal to ensure proper operation.

Below is an example of how to interface the 3.5 In TFT Display Module with an Arduino UNO using the SPI interface. Note that a level shifter is required for the Arduino UNO, as it operates at 5V logic.

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7789.h> // ST7789 driver (compatible with ST7769)

// Define SPI pins
#define TFT_CS    10  // Chip Select pin
#define TFT_RST   9   // Reset pin
#define TFT_DC    8   // Data/Command pin

// Initialize the display object
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);
  Serial.println("Initializing TFT Display...");

  // Initialize the display
  tft.init(320, 480); // Set resolution (320x480)
  tft.setRotation(1); // Set display orientation

  // Fill the screen with a color
  tft.fillScreen(ST77XX_BLACK);
  tft.setTextColor(ST77XX_WHITE);
  tft.setTextSize(2);
  tft.setCursor(10, 10);
  tft.println("Hello, TFT!");
}

void loop() {
  // Add your code here to update the display
}

1. Display Not Turning On:

   • Verify the power supply connections (VCC and GND).
   • Check the backlight connections (LED+ and LED-).
   • Ensure the SPI pins are correctly connected to the microcontroller.

2. No Image or Distorted Graphics:

   • Confirm the SPI clock speed is within the display's supported range.
   • Check the initialization code for proper configuration of the ST7769 driver.
   • Ensure the reset signal is properly applied during startup.

3. Backlight Flickering:

   • Verify the backlight power supply voltage and current.
   • Use a stable power source and add a decoupling capacitor if needed.

4. Touchscreen Not Responding (if applicable):

   • Ensure the touchscreen controller (if present) is properly connected and initialized.
   • Check the library documentation for touchscreen-specific functions.

Q: Can I use this display with a 5V microcontroller?
A: Yes, but you must use level shifters to convert the 5V logic signals to 3.3V to avoid damaging the display.

Q: Is this display compatible with Raspberry Pi?
A: Yes, the display can be used with Raspberry Pi via the SPI interface. Ensure you use the appropriate driver and configuration.

Q: How do I adjust the brightness of the backlight?
A: You can adjust the brightness by varying the voltage or using a PWM signal on the LED+ pin.

Q: Can I use this display in outdoor environments?
A: The display is rated for operation between -20°C and 70°C, but it is not sunlight-readable. Consider using a display with higher brightness for outdoor use.