How to Use ST7789 With MicroSD Reader: Examples, Pinouts, and Specs

The ST7789 is a compact color display driver designed for small screens with a resolution of 240x240 pixels. It is widely used in embedded systems due to its vibrant color rendering and efficient performance. This module also includes an integrated MicroSD card reader, enabling convenient storage and retrieval of images, fonts, and other data. Its compact size and versatile functionality make it ideal for portable devices, IoT projects, and graphical user interfaces.

• Portable devices such as smartwatches and handheld gadgets
• IoT projects requiring graphical displays
• Data visualization in embedded systems
• Image and font rendering using MicroSD storage
• Educational and prototyping projects with microcontrollers like Arduino and Raspberry Pi

To use the ST7789 display with an Arduino UNO, connect the pins as follows:

For the MicroSD reader, connect the pins as follows:

Below is an example code to initialize the ST7789 display and display a simple message. It also includes initialization for the MicroSD card.

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

// Define pins for ST7789
#define TFT_CS    10  // Not used, but required by library
#define TFT_RST   8   // Reset pin
#define TFT_DC    9   // Data/Command pin

// Define pin for MicroSD card
#define SD_CS     4   // Chip Select for MicroSD

// Initialize ST7789 display
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  while (!Serial);

  // Initialize the display
  tft.init(240, 240);  // Initialize with 240x240 resolution
  tft.setRotation(1);  // Set display rotation
  tft.fillScreen(ST77XX_BLACK);  // Clear screen with black color
  tft.setTextColor(ST77XX_WHITE);
  tft.setTextSize(2);
  tft.setCursor(10, 10);
  tft.println("Hello, ST7789!");

  // Initialize MicroSD card
  if (!SD.begin(SD_CS)) {
    Serial.println("MicroSD initialization failed!");
    tft.setCursor(10, 50);
    tft.println("SD Init Failed!");
    return;
  }
  Serial.println("MicroSD initialized.");
  tft.setCursor(10, 50);
  tft.println("SD Init Success!");
}

void loop() {
  // Main loop does nothing in this example
}

1. Voltage Levels: Ensure the module operates at 3.3V. Using 5V logic without level shifters may damage the display.
2. SPI Speed: Use a moderate SPI clock speed (e.g., 4 MHz) to ensure stable communication.
3. MicroSD Formatting: Format the MicroSD card to FAT32 before use.
4. Backlight Control: Connect the BLK pin to GND to enable the backlight. For dimming, use a PWM pin.

1. Display Not Turning On

   • Cause: Incorrect wiring or insufficient power supply.
   • Solution: Double-check connections and ensure the VCC pin is connected to a stable 3.3V source.

2. MicroSD Card Not Detected

   • Cause: Improper formatting or loose connections.
   • Solution: Format the card to FAT32 and ensure the CS, MOSI, MISO, and SCK pins are correctly connected.

3. Flickering or Noisy Display

   • Cause: High SPI clock speed or poor power supply.
   • Solution: Reduce the SPI clock speed and use a decoupling capacitor near the VCC and GND pins.

4. Text or Graphics Not Displaying Correctly

   • Cause: Incorrect initialization or wrong library settings.
   • Solution: Verify the display resolution and initialization code. Ensure the correct library is installed.

1. Can I use the ST7789 with a 5V microcontroller?

   • Yes, but you must use level shifters to convert 5V logic to 3.3V.

2. What is the maximum MicroSD card size supported?

   • The module typically supports MicroSD cards up to 32GB formatted in FAT32.

3. Can I control the backlight brightness?

   • Yes, connect the BLK pin to a PWM-capable pin on your microcontroller for brightness control.

4. Is the ST7789 compatible with Raspberry Pi?

   • Yes, the ST7789 can be used with Raspberry Pi using SPI and appropriate libraries like luma.lcd.

By following this documentation, you can effectively integrate the ST7789 with MicroSD reader into your projects for vibrant displays and convenient data storage.