Small color TFT displays are among the most popular display types in Arduino and ESP32 projects. They are inexpensive, widely available and capable of showing full-color graphics, menus and simple user interfaces.
This article explains how TFT LCD displays work, compares the common ST7735 and ST7789 controllers, and shows when to use each type.
What Is a TFT LCD Display?
TFT stands for Thin-Film Transistor. A TFT LCD is a type of liquid crystal display where each pixel is actively controlled by a transistor.
Unlike OLED displays, TFT LCDs require a backlight to be visible.
- Each pixel controls light from the backlight
- Full RGB color support
- Higher resolution than character LCDs
- Typically uses SPI or parallel interface
Small TFT displays are commonly used in embedded systems for dashboards, menus and graphical feedback.
ST7735 Displays
The ST7735 is one of the most widely used controllers for small TFT displays.
Typical features:
- Common resolution: 128x160 pixels
- SPI interface
- Compact modules (often around 1.8 inch)
- Good library support in Arduino ecosystem
- Low cost
ST7735 displays are often used in beginner projects because they are easy to connect and well supported by libraries such as Adafruit GFX.
Advantages of ST7735
- Very common and well documented
- Works with many existing examples
- Good balance between cost and performance
Limitations of ST7735
- Lower resolution compared with newer displays
- Smaller screen size
ST7789 Displays
The ST7789 is a more modern TFT controller and has become very popular for slightly larger and higher-resolution displays.
Typical features:
- Common resolutions: 240x240, 240x320
- SPI interface
- Available in square and rectangular formats
- Often used in 1.3 inch to 2.4 inch displays
ST7789 displays provide significantly more pixels than ST7735 displays, which allows for better graphics and more detailed user interfaces.
Advantages of ST7789
- Higher resolution
- Better for graphical interfaces
- Widely available in modern modules
Limitations of ST7789
- Requires more memory for frame buffers
- Slightly higher cost than basic ST7735 modules
ST7735 vs ST7789 Comparison
| Feature | ST7735 | ST7789 |
|---|---|---|
| Typical resolution | 128x160 | 240x240 or 240x320 |
| Interface | SPI | SPI |
| Typical size | ~1.8 inch | 1.3 to 2.4 inch |
| Graphics detail | Basic | Higher detail |
| Library support | Excellent | Excellent |
| Typical use | Simple UI, small projects | More advanced UI, dashboards |
Wiring and Interface
Most ST7735 and ST7789 modules use SPI.
Typical connections:
- MOSI (data)
- SCLK (clock)
- CS (chip select)
- DC (data/command)
- RESET (optional)
SPI allows relatively fast updates, which is important for drawing graphics and refreshing the screen.
Performance Considerations
TFT displays require more data than text displays. Every pixel must be updated through the interface.
Important factors:
- SPI speed affects refresh rate
- Higher resolution needs more data transfer
- Full-screen updates are slower than partial updates
- Microcontroller performance matters
On slower microcontrollers, updating a full 240x320 screen can take noticeable time.
Power Consumption
The main power consumption in TFT displays comes from the backlight.
- Backlight current is often higher than logic current
- Brightness directly affects power consumption
- Some modules allow PWM dimming of the backlight
For battery-powered projects, reducing backlight brightness can significantly increase runtime.
Typical Use Cases
- Menu-driven user interfaces
- Sensor dashboards
- Simple games
- Visual feedback systems
- Portable devices with graphical output
ST7735 is suitable for smaller, simpler projects. ST7789 is better when more detail and screen space are needed.
Important Practical Notes
- Most modules use 3.3V logic
- Some boards include level shifting, but do not assume it
- Always check the exact display resolution
- Different modules may use different pin labels
- Use optimized libraries for better performance
Conclusion
ST7735 and ST7789 TFT displays are both excellent choices for small color screens in embedded projects. The ST7735 is ideal for simple and low-cost applications, while the ST7789 provides higher resolution and better visual quality for more advanced interfaces.
For most new designs, ST7789 is often the better long-term choice, while ST7735 remains a practical option for basic projects and cost-sensitive designs.