How to Use 1.54'' TFT Display 240x240 spi ST7789: Examples, Pinouts, and Specs

The 1.54-inch TFT display is a compact, high-resolution screen with a resolution of 240x240 pixels. It uses the ST7789 driver and communicates via the SPI (Serial Peripheral Interface) protocol. This display is ideal for applications requiring a vibrant and colorful interface in a small form factor, such as smartwatches, IoT devices, handheld instruments, and embedded systems.

• Smartwatches and wearable devices
• IoT dashboards and status displays
• Portable gaming consoles
• Industrial control panels
• DIY electronics projects with microcontrollers (e.g., Arduino, Raspberry Pi)

1. Power Supply: Connect the VCC pin to a 3.3V power source and the GND pin to ground.
2. SPI Communication: Connect the SCL (SPI clock) and SDA (SPI data) pins to the corresponding SPI pins on your microcontroller.
3. Control Pins:
   • Connect the RES pin to a GPIO pin on your microcontroller for resetting the display.
   • Connect the DC pin to a GPIO pin to toggle between data and command modes.
4. Backlight: Connect the BLK pin to 3.3V for constant backlight or to a PWM-capable GPIO pin for brightness control.

• Voltage Levels: Ensure all logic signals are 3.3V. If using a 5V microcontroller (e.g., Arduino UNO), use level shifters to avoid damaging the display.
• SPI Speed: The ST7789 supports high SPI clock speeds, but start with a moderate speed (e.g., 4 MHz) to ensure stable communication.
• Initialization: The display requires specific initialization commands to configure the ST7789 driver. Use a compatible library to simplify this process.
• Backlight Control: Use PWM to adjust the backlight brightness for power savings and better user experience.

Below is an example of how to use the 1.54'' TFT display with an Arduino UNO using the Adafruit ST7789 library.

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7789.h> // ST7789 driver library
#include <SPI.h>             // SPI library

// Define pins for the display
#define TFT_CS    10  // Chip select pin (not used, tie to GND)
#define TFT_RST   9   // Reset pin
#define TFT_DC    8   // Data/Command pin

// Create an instance of the display
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

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

  // Initialize the display
  tft.init(240, 240); // Initialize with 240x240 resolution
  tft.setRotation(0); // 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, World!");
}

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

• Install the Adafruit GFX and Adafruit ST7789 libraries via the Arduino Library Manager before running the code.
• Adjust the TFT_CS, TFT_RST, and TFT_DC pin definitions to match your wiring.

1. Display Not Turning On:

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

2. No Output on the Screen:

   • Check the SPI connections (SCL and SDA) and ensure they are correctly wired.
   • Confirm that the RES and DC pins are connected to the correct GPIO pins.
   • Ensure the display initialization code matches the ST7789 driver requirements.

3. Flickering or Unstable Display:

   • Reduce the SPI clock speed in your code.
   • Check for loose or poor-quality connections.

4. Incorrect Colors or Artifacts:

   • Verify that the display is initialized in 16-bit color mode.
   • Ensure the data being sent to the display matches the expected format.

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

Q: Is this display compatible with Raspberry Pi?
A: Yes, the display can be used with Raspberry Pi. Use the SPI interface and configure the ST7789 driver in your software.

Q: Can I daisy-chain multiple displays?
A: No, the ST7789 does not support daisy-chaining. Each display requires a separate SPI connection.