Documentation

Overview

The ESP32 LVGL 2.8" Smart Display — better known in the maker community as the Sunton ESP32-2432S028R or simply the "Cheap Yellow Display" (CYD) — is one of the best value all-in-one ESP32 dev boards you can buy. You get an ESP-WROOM-32 module, a 2.8" 240x320 ILI9341 TFT, a resistive touch panel driven by an XPT2046, a microSD slot, a small speaker output, and a USB programming port, all on a single board for about the price of a bare ESP32 plus a discrete display.

What makes it especially attractive is software support. The board is fully compatible with the LVGL graphics library, TFT_eSPI, and LovyanGFX on the Arduino IDE side, plus various MicroPython display drivers. If you want a Wi-Fi connected smart-home control panel, a portable instrument display, or a small dashboard for sensor data, this board cuts your bring-up time dramatically.

The trade-off is that you have to use the specific GPIOs the board manufacturer chose — the display, touch, and SD share the same SPI bus but have separate chip-select lines, and the backlight is on GPIO21. Once you have the right pin map plugged into TFT_eSPI's User_Setup.h (or your LVGL config), everything works flawlessly.

At a Glance

Specifications

Pinout Diagram

Wiring Guide

Code Examples

Arduino IDE — TFT_eSPI setup for the CYD (User_Setup.h snippet):

In User_Setup.h inside the TFT_eSPI library folder, comment out the default setup and use this:

#define ILI9341_DRIVER
#define TFT_WIDTH  240
#define TFT_HEIGHT 320

#define TFT_MISO 12
#define TFT_MOSI 13
#define TFT_SCLK 14
#define TFT_CS   15
#define TFT_DC    2
#define TFT_RST  -1   // tied to ESP32 reset
#define TFT_BL   21
#define TFT_BACKLIGHT_ON HIGH

#define TOUCH_CS 33

#define SPI_FREQUENCY       55000000
#define SPI_READ_FREQUENCY  20000000
#define SPI_TOUCH_FREQUENCY  2500000

#define LOAD_GLCD
#define LOAD_FONT2
#define LOAD_FONT4
#define LOAD_GFXFF
#define SMOOTH_FONT

Then a minimal sketch to verify the panel is alive:

#include <TFT_eSPI.h>

TFT_eSPI tft = TFT_eSPI();

void setup() {
  pinMode(21, OUTPUT);
  digitalWrite(21, HIGH);   // backlight ON
  tft.init();
  tft.setRotation(1);
  tft.fillScreen(TFT_BLACK);
  tft.setTextColor(TFT_YELLOW, TFT_BLACK);
  tft.setTextSize(2);
  tft.setCursor(20, 100);
  tft.println("CYD is alive!");
}

void loop() {}

ESP32 + LVGL — Hello World with a button:

#include <lvgl.h>
#include <TFT_eSPI.h>

static const uint16_t SCREEN_W = 320;
static const uint16_t SCREEN_H = 240;

TFT_eSPI tft = TFT_eSPI();
static lv_disp_draw_buf_t draw_buf;
static lv_color_t buf[SCREEN_W * 10];

void my_disp_flush(lv_disp_drv_t *disp, const lv_area_t *area, lv_color_t *color_p) {
  uint32_t w = area->x2 - area->x1 + 1;
  uint32_t h = area->y2 - area->y1 + 1;
  tft.startWrite();
  tft.setAddrWindow(area->x1, area->y1, w, h);
  tft.pushColors((uint16_t *)&color_p->full, w * h, true);
  tft.endWrite();
  lv_disp_flush_ready(disp);
}

void setup() {
  pinMode(21, OUTPUT); digitalWrite(21, HIGH);
  tft.begin();
  tft.setRotation(1);

  lv_init();
  lv_disp_draw_buf_init(&draw_buf, buf, NULL, SCREEN_W * 10);

  static lv_disp_drv_t disp_drv;
  lv_disp_drv_init(&disp_drv);
  disp_drv.hor_res = SCREEN_W;
  disp_drv.ver_res = SCREEN_H;
  disp_drv.flush_cb = my_disp_flush;
  disp_drv.draw_buf = &draw_buf;
  lv_disp_drv_register(&disp_drv);

  lv_obj_t *btn = lv_btn_create(lv_scr_act());
  lv_obj_center(btn);
  lv_obj_t *label = lv_label_create(btn);
  lv_label_set_text(label, "Hello CYD");
}

void loop() {
  lv_timer_handler();
  delay(5);
}

MicroPython — quick check using ili9341 driver:

from machine import Pin, SPI
import ili9341

# Backlight ON
Pin(21, Pin.OUT).value(1)

spi = SPI(1, baudrate=40000000, sck=Pin(14), mosi=Pin(13), miso=Pin(12))
display = ili9341.Display(spi, dc=Pin(2), cs=Pin(15), rst=Pin(12))

display.clear(ili9341.color565(0, 0, 0))
display.draw_text8x8(60, 100, "Hello CYD", ili9341.color565(255, 220, 0))

Frequently Asked Questions