Building a Round Smartwatch Dashboard: Interfacing the 1.28-inch GC9A01 TFT LCD Module

Most hobbyist screens are square or rectangular, which limits your options when building wearables like smartwatches or compact circular dashboard gauges. The 1.28 Inch TFT LCD Display Module Round RGB 240*240 (powered by the GC9A01 driver) offers a beautiful circular IPS screen with wide viewing angles, perfect for slick, modern designs.

In this guide, we will connect the GC9A01 round display to an ESP32 or Arduino, and set up a reliable power bench to test high-draw components using a 100W USB-C decoy trigger board and 11.1V LiPo batteries.

Featured Circuit Diagram (SPI Connection)

       [ ESP32 / Development Board ]                       [ GC9A01 Round Display ]
      +─────────────────────────────+                      +──────────────────────+
      |  VCC (3.3V Output)          | ───────────────────> |  VCC (3.3V Power)    |
      |  GND                        | ───────────────────> |  GND                 |
      |  GPIO 18 (SPI Clock SCK)    | ───[ Serial Clock ]─>|  SCL                 |
      |  GPIO 23 (SPI Data MOSI)    | ───[ Serial Data  ]─>|  SDA                 |
      |  GPIO 4                     | ───[ Reset Line   ]─>|  RES                 |
      |  GPIO 2                     | ───[ Data/Command ]─>|  DC                  |
      |  GPIO 15                    | ───[ Chip Select  ]─>|  CS                  |
      |  GPIO 13 (PWM Pin)          | ───[ Backlight En ]─>|  BLK                 |
      +─────────────────────────────+                      +──────────────────────+

Featured Components

• Round Display: 1.28 Inch TFT LCD Display Module Round RGB 240*240 GC9A01 Driver
• USB Decoy Power: 100W 5A USB Type C QC Decoy Trigger Board
• Battery Pack: 11.1V 2200mAh 35C 3S Lipo Battery XT60 Plug
• Mains Adapter Plug: 10CM DC 9V 5.5*2.1mm Battery Button Power Plug

Round Display Graphics Code

We use the popular Adafruit_GFX and Adafruit_GC9A01A libraries to initialize the round display:

#include <Adafruit_GFX.h>
#include <Adafruit_GC9A01A.h>

#define TFT_CS   10
#define TFT_DC    7
#define TFT_RST   8

Adafruit_GC9A01A tft = Adafruit_GC9A01A(TFT_CS, TFT_DC, TFT_RST);

void setup() {
  Serial.begin(9600);
  tft.begin();
  tft.setRotation(0);
  tft.fillScreen(GC9A01A_BLACK);
  
  // Draw circular dial outline
  tft.drawCircle(120, 120, 115, GC9A01A_BLUE);
  tft.drawCircle(120, 120, 110, GC9A01A_WHITE);
  
  // Render dashboard text in the center
  tft.setCursor(65, 110);
  tft.setTextColor(GC9A01A_GREEN);
  tft.setTextSize(2);
  tft.println("SYSTEM OK");
}

void loop() {
  // Update dashboard telemetry here
}

Powering the Wearable & Bench Testing

During development, you may want to simulate high-draw wireless transmission or drive multiple servos alongside the display.

• Using 3S LiPo Batteries: A 3S battery provides an 11.1V nominal output (up to 12.6V fully charged). Since your display and MCU need 3.3V/5V, use a step-down regulator to prevent burning your chips.
• USB-C Decoy Trigger Boards: Rather than relying on a heavy lab power supply, you can use a USB Type-C QC Decoy board. Setting the onboard jumpers tells a standard USB-PD laptop charger to output exactly 9V, 12V, or 20V directly to your breadboard rails.