You just bought a 2.4-inch or 3.5-inch TFT LCD shield for your Arduino. You plug it in, upload a sketch, and… nothing shows up. Just a white screen. Or worse — random lines, pixels, or gibberish.
That’s when the real questions begin:
“How does this screen even work?”
“Why is my text not displaying?”
“Is the library wrong or is my screen dead?”
If you’ve been there, trust me — you’re not alone. In this guide, we’ll not only fix that, but we’ll understand how text is displayed, what’s going on inside the LCD, and why this first step is the most important for using your display in future projects.
What You’ll Learn in This Post
- The real way LCD shields work with Arduino
- How the text is drawn on the screen
- The difference between pixels and characters
- The exact libraries and code that work (no guessing)
- And most importantly:
How to make sure it actually shows something on your screen
How Does This TFT LCD Shield Actually Work?
1. Parallel Interface (Not SPI)
Unlike small OLEDs or some TFT modules that use SPI, these bigger shields (like your 2.4″ red or 3.5″ blue shield) use a parallel interface — typically 8 data lines and control lines like RD, WR, CS, etc.
That means:
It plugs directly into Arduino UNO, using almost all digital pins.
It transfers 8 bits at once (instead of 1 bit like SPI), making it faster.
It needs a specific library that knows how to talk to this screen’s controller IC (like ILI9486 or ST7789V in your case).
2. How Text Appears on the LCD
When you write text like:
cppCopyEdittft.setCursor(10, 50);
tft.setTextColor(WHITE);
tft.setTextSize(2);
tft.println("Hello World");
Here’s what really happens behind the scenes:
| Command | What it does |
|---|---|
setCursor(x, y) | Sets the pixel where the text will start |
setTextColor() | Chooses what color the text pixels will be |
setTextSize() | Multiplies the font size (2×2, 3×3 pixels per character) |
println() | Converts your text into pixel data and sends it to the LCD |
Each character you write is drawn using pixels, using a predefined font inside the library.
So Hello is not just a word — it’s a group of rectangles made of colored pixels.
3. Why Text Sometimes Doesn’t Show
- You didn’t run
tft.begin(ID) - Your text color is same as background (e.g. white on white)
- Your cursor is off-screen
- Screen isn’t correctly initialized
Always use this pattern:
cppCopyEdituint16_t ID = tft.readID();
tft.begin(ID);
tft.fillScreen(BLACK); // Clear screen with background
Sample Code to Display Text
Here is the simplest working sketch for your TFT LCD shield:
cppCopyEdit#include <MCUFRIEND_kbv.h>
#include <Adafruit_GFX.h>
#define BLACK 0x0000
#define WHITE 0xFFFF
MCUFRIEND_kbv tft;
void setup() {
Serial.begin(9600);
uint16_t ID = tft.readID();
tft.begin(ID);
tft.setRotation(1);
tft.fillScreen(BLACK);
tft.setCursor(30, 60);
tft.setTextColor(WHITE);
tft.setTextSize(2);
tft.println("Hello, World!");
}
void loop() {}
Upload this with your shield connected, and your screen should light up with the message.
Recap: Why This Is Step 1 Before Anything Else
Learning how text works helps you later when you:
- Add sensors and want to display values
- Build a menu-based UI (like “Start”, “Stop”, “Back”)
- Show status messages or debug information
- Add real-time data or graphics later
It’s the foundation of making your display project successful.
What’s Next?
Now that you understand how text is displayed:
- We’ll move to drawing shapes and graphics (next blog)
- Then to creating animations or motion
- And finally, building an actual user interface or machine screen