Introduction

The ESP32 GC9A01 TFT display is a powerful color display module widely used in modern embedded electronics projects. Its round design makes it perfect for smartwatch interfaces, digital clocks, IoT dashboards, wearable devices, and compact graphical displays.

In this tutorial, we will learn how to connect the ESP32 GC9A01 TFT display with ESP32, install the required Arduino libraries, configure SPI communication, and display graphics and text using Arduino IDE.

The ESP32 is an excellent microcontroller for this project because it provides:

• High-speed dual-core processing
• Built-in WiFi
• Bluetooth connectivity
• Multiple GPIO pins
• Fast SPI communication
• Low power operation

By combining ESP32 with the ESP32 GC9A01 TFT display, we can create colorful graphical interfaces for IoT and embedded applications.

Project Features

This ESP32 GC9A01 TFT display project can display:

• Text
• Colors
• Shapes
• Graphics
• Sensor values
• Animations
• User interfaces

Applications include:

• ESP32 smartwatch
• IoT monitoring display
• Weather station
• Digital dashboard
• Robotics controller
• Home automation screen

Required Components

About GC9A01 Round TFT Display

The GC9A01 is a color TFT display controller designed for small round LCD screens.

Display Specifications

Required Arduino Libraries

Install these three libraries before uploading the code.

1. Adafruit GFX Library

2. Adafruit GC9A01A Library

This library controls the GC9A01 display driver.

It manages:

• Display initialization
• Pixel communication
• Screen commands
• Color handling

3. SPI Library

SPI is the communication protocol used between ESP32 and GC9A01.

The ESP32 Arduino core already includes this library.

Installing Libraries in Arduino IDE

Open Arduino IDE:

Sketch
   ↓
Include Library
   ↓
Manage Libraries

Sketch
   ↓
Include Library
   ↓
Manage Libraries

Search and install:

Adafruit GFX Library

Adafruit GFX Library

Adafruit GC9A01A

Adafruit GC9A01A

SPI library is already available.

ESP32 to GC9A01 Wiring Connection

The GC9A01 uses SPI communication.

Connection Table

Pin Definition

In Arduino code we define:

#define TFT_DC 4
#define TFT_CS 2
#define TFT_MOSI 21
#define TFT_SCLK 22

#define TFT_DC 4
#define TFT_CS 2
#define TFT_MOSI 21
#define TFT_SCLK 22

Meaning:

Circuit Diagram

Complete ESP32 GC9A01 Arduino Code

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"


#define TFT_CS 2
#define TFT_DC 4

#define TFT_MOSI 21
#define TFT_SCLK 22


Adafruit_GC9A01A tft(TFT_CS, TFT_DC);


void setup()
{
  Serial.begin(115200);

  Serial.println("GC9A01 ESP32 Test");


  SPI.begin(
    TFT_SCLK,
    -1,
    TFT_MOSI,
    TFT_CS
  );


  tft.begin();


  tft.setRotation(0);


  tft.fillScreen(GC9A01A_BLACK);


  tft.setCursor(20,100);

  tft.setTextColor(GC9A01A_GREEN);

  tft.setTextSize(2);

  tft.println("ESP32");


  tft.setCursor(15,130);

  tft.println("GC9A01 TFT");

}


void loop()
{

}

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"


#define TFT_CS 2
#define TFT_DC 4

#define TFT_MOSI 21
#define TFT_SCLK 22


Adafruit_GC9A01A tft(TFT_CS, TFT_DC);


void setup()
{
  Serial.begin(115200);

  Serial.println("GC9A01 ESP32 Test");


  SPI.begin(
    TFT_SCLK,
    -1,
    TFT_MOSI,
    TFT_CS
  );


  tft.begin();


  tft.setRotation(0);


  tft.fillScreen(GC9A01A_BLACK);


  tft.setCursor(20,100);

  tft.setTextColor(GC9A01A_GREEN);

  tft.setTextSize(2);

  tft.println("ESP32");


  tft.setCursor(15,130);

  tft.println("GC9A01 TFT");

}


void loop()
{

}

Complete Code Explanation

Including Libraries

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"

#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"

These libraries provide:

SPI

Handles communication between ESP32 and TFT.

Adafruit GFX

Provides drawing functions.

GC9A01A

Controls the display hardware.

Defining TFT Pins

#define TFT_CS 2
#define TFT_DC 4

#define TFT_CS 2
#define TFT_DC 4

CS Pin

Chip Select activates the TFT display during SPI communication.

Connected to:

ESP32 GPIO 2

ESP32 GPIO 2

DC Pin

Data/Command pin tells the display whether the received information is:

• A command
• Display data

Connected to:

ESP32 GPIO 4

ESP32 GPIO 4

SPI Pin Configuration

#define TFT_MOSI 21
#define TFT_SCLK 22

#define TFT_MOSI 21
#define TFT_SCLK 22

MOSI

GPIO21 sends data from ESP32 to display.

Used for:

• Text
• Images
• Graphics

SCLK

GPIO22 provides SPI clock timing.

It synchronizes communication.

Creating TFT Object

Adafruit_GC9A01A tft(TFT_CS,TFT_DC);

Adafruit_GC9A01A tft(TFT_CS,TFT_DC);

Creates a display object called:

tft

tft

This object controls the GC9A01 display.

Setup Function

The setup function runs once after ESP32 starts.

It performs:

• Serial initialization
• SPI setup
• Display startup
• Screen configuration

Serial Communication

Serial.begin(115200);

Serial.begin(115200);

Starts communication with Serial Monitor.

Useful for debugging.

Starting SPI

SPI.begin(TFT_SCLK,-1,TFT_MOSI,TFT_CS);

SPI.begin(TFT_SCLK,-1,TFT_MOSI,TFT_CS);

SPI format:

SPI.begin(clock, MISO, MOSI, CS)

SPI.begin(clock, MISO, MOSI, CS)

ESP32 connection:

Starting Display

tft.begin();

tft.begin();

Initializes:

• GC9A01 controller
• Display memory
• SPI communication

Screen Rotation

tft.setRotation(0);

tft.setRotation(0);

Controls display direction.

Options:

0 Normal
1 90 Degree
2 180 Degree
3 270 Degree

0 Normal
1 90 Degree
2 180 Degree
3 270 Degree

Clearing Display

tft.fillScreen(GC9A01A_BLACK);

tft.fillScreen(GC9A01A_BLACK);

Sets complete screen background color.

Available colors:

BLACK
RED
GREEN
BLUE
WHITE
YELLOW

BLACK
RED
GREEN
BLUE
WHITE
YELLOW

Setting Text Position

tft.setCursor(20,100);

tft.setCursor(20,100);

Sets the location where text starts.

Format:

setCursor(X,Y)

setCursor(X,Y)

Setting Text Color

tft.setTextColor(GC9A01A_GREEN);

tft.setTextColor(GC9A01A_GREEN);

Changes text color.

Example:

tft.setTextColor(GC9A01A_RED);

tft.setTextColor(GC9A01A_RED);

Setting Font Size

tft.setTextSize(2);

tft.setTextSize(2);

Controls text size.

Examples:

1 = Small
2 = Medium
3 = Large

1 = Small
2 = Medium
3 = Large

Printing Text

tft.println("ESP32");

tft.println("ESP32");

Displays text on the TFT screen.

Output:

ESP32
GC9A01 TFT

ESP32
GC9A01 TFT

Loop Function

void loop()
{

}

void loop()
{

}

The loop runs continuously.

It is empty because the display only shows fixed text.

For animation:

void loop()
{
 tft.fillCircle(120,120,30,GC9A01A_RED);
 delay(500);
}

void loop()
{
 tft.fillCircle(120,120,30,GC9A01A_RED);
 delay(500);
}

Graphics Examples

Draw Circle

tft.drawCircle(120,120,50,GC9A01A_BLUE);

tft.drawCircle(120,120,50,GC9A01A_BLUE);

Fill Rectangle

tft.fillRect(50,50,100,50,GC9A01A_RED);

tft.fillRect(50,50,100,50,GC9A01A_RED);

Draw Line

tft.drawLine(0,0,200,200,GC9A01A_GREEN);

tft.drawLine(0,0,200,200,GC9A01A_GREEN);

Troubleshooting

White Screen

Check:

• 3.3V power
• CS pin
• DC pin
• SPI wiring

Nothing Appears

Try:

• Verify library installation
• Check display address
• Check solder connections

Wrong Orientation

Change:

tft.setRotation(1);

tft.setRotation(1);

Project Applications

Smart Watch

Create a round user interface similar to commercial watches.

IoT Dashboard

Display:

• Temperature
• Humidity
• Sensor data

Digital Clock

Show:

• Time
• Date
• Weather

Robotics

Display robot status and controls.

Advantages of ESP32 + GC9A01

• Low-cost hardware
• Fast graphics
• Compact design
• Wireless capability
• Easy Arduino programming
• Suitable for beginners

Conclusion

The ESP32 and GC9A01 round TFT display combination is a powerful solution for creating compact graphical projects. With only a few SPI connections and simple Arduino programming, you can build advanced displays for IoT, wearable devices, automation systems, and embedded applications.