Very Poor Display and Wrong Colors on my T-HMI screen

How-to
1

What do you want to achieve?

I get very poor display output on my display screen and the colors are wrong for buttons and label background.

What have you tried so far?

  • Tried increasing buffer size from 320 * 10 to 320 * 40.
  • Tried using two buffers instead of one inlv_disp_draw_buf_init function
  • Made sure my pins are configured correctly inside User_Setup.h of the TFT_eSPI library.

Code to reproduce

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

// Display buffer
static lv_disp_draw_buf_t draw_buf;
static lv_color_t buf[320 * 40];

TFT_eSPI tft = TFT_eSPI();

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.pushPixels((uint16_t *)color_p, w * h);
  tft.endWrite();
  
  lv_disp_flush_ready(disp);
}

void setup() {
  Serial.begin(115200);
  
  // Power control
  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH);
  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH);
  
  // Backlight control
  pinMode(38, OUTPUT);
  digitalWrite(38, HIGH);

  // TFT initialization
  tft.begin();
  tft.setRotation(1);
  
  // LVGL initialization
  lv_init();
  lv_disp_draw_buf_init(&draw_buf, buf, NULL, 320 * 40);
  
  static lv_disp_drv_t disp_drv;
  lv_disp_drv_init(&disp_drv);
  disp_drv.hor_res = 320;
  disp_drv.ver_res = 240;
  disp_drv.flush_cb = my_disp_flush;
  disp_drv.draw_buf = &draw_buf;
  lv_disp_drv_register(&disp_drv);
}

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

// Pin setup in User_Setup.h inside TFT_eSPI library:
#define USER_SETUP_INFO "User_Setup"
#define ST7789_DRIVER
#define TFT_WIDTH  320
#define TFT_HEIGHT 240
#define TFT_MOSI 48
#define TFT_SCLK 8
#define TFT_CS   6
#define TFT_DC   7
#define TFT_RST  -1
#define SPI_FREQUENCY 40000000
#define SPI_READ_FREQUENCY  20000000
#define SPI_TOUCH_FREQUENCY  2500000

#define LOAD_GLCD
#define LOAD_FONT2
#define LOAD_FONT4 
#define LOAD_FONT6 
#define LOAD_FONT7  
#define LOAD_FONT8
#define LOAD_GFXFF
#define SMOOTH_FONT

Screenshot and/or video

WIN_20250709_16_20_05_Pro
WIN_20250709_16_20_05_Pro447×695 52.8 KB

Environment

  • MCU/MPU/Board: I am using T-HMI (Resistive Touch) with ESP32-S3 and a ST7789 driver display.
  • LVGL version: 8.3.5