Two examples of using the 1.28" TFT LCD and an ESP32. The first example is extremely simple; However it flickers. The second one avoids the flicker by using the sprite function.

gistfile1.txt

// First example - extremely simple
#include <TFT_eSPI.h> // Graphics and font library for ST7735 driver chip
#include <SPI.h>

TFT_eSPI tft = TFT_eSPI();  // Invoke library, pins defined in User_Setup.h

unsigned long displayWeightLastTime = 0;
unsigned long displayWeightDelay = 1000;
unsigned long currentMillis = 0;

float weight = 123.99;
byte xpos = 40;
byte ypos = 90;
void setup(void) {
  tft.init();
  tft.setRotation(0);
  tft.fillScreen(TFT_BLACK);
  tft.setTextColor(TFT_YELLOW, TFT_BLACK); // Note: the new fonts do not draw the background colour
}

void loop() {
  currentMillis = millis();
  if (currentMillis - displayWeightLastTime >= displayWeightDelay) {
    displayWeight();
    displayWeightLastTime = currentMillis;
  }
}
void displayWeight() {
  int fontWeight = 6;
  tft.fillScreen(TFT_BLACK); // Optional: clear the screen to update the weight display
  tft.setTextColor(TFT_ORANGE); // Set text color to orange
  char buff[10]; // Buffer to hold the weight string
  // Convert the float to a string with 1 decimal place
  snprintf(buff, sizeof(buff), "%.2f", weight);
  // Use drawString to display the weight at the specified position
  tft.drawString(buff, xpos, ypos, fontWeight); // The last parameter is the font size, adjust as needed
}

// The second example begins here.  It uses the 'sprite' approach to avoid flicker.
#include <TFT_eSPI.h> // Graphics and font library for ST7735 driver chip
#include <SPI.h>

TFT_eSPI tft = TFT_eSPI();  // Invoke TFT library
TFT_eSprite spr = TFT_eSprite(&tft); // Create sprite

int spriteWidth = 220; // Width of the sprite slightly larger than the circle's diameter
int spriteHeight = 220; // Height as well, to ensure the circle fits

float weight = 123.99;

void setup(void) {
  tft.init();
  tft.setRotation(0);
  tft.fillScreen(TFT_BLACK);

  // Initialize sprite with enough space for the circle and text
  spr.createSprite(spriteWidth, spriteHeight);
  spr.setTextColor(TFT_YELLOW, TFT_BLACK); // Set sprite text color
}

void loop() {
  // Display weight and update every 1 second
  displayWeight();
  delay(1000); // Simple delay for demonstration, adjust as needed
}

void displayWeight() {
  spr.fillSprite(TFT_BLACK); // Clear the sprite for fresh drawing

  // Drawing the circle centered in the sprite
  int circleDiameter = 215;
  int circleRadius = circleDiameter / 2;
  int circleX = spriteWidth / 2; // Center of the sprite width
  int circleY = spriteHeight / 2; // Center of the sprite height
  spr.drawCircle(circleX, circleY, circleRadius, TFT_RED); // Draw the circle centered in the sprite
  
  spr.setTextSize(4); // Adjust size of the displayed weight as needed

  // Adding an additional offset moves the text down within the circle
  int offsetY = 16; // Adjust to lower the text below the center point
  int textY = circleY + offsetY - spr.fontHeight() / 2;

  // Display the weight text with adjusted y position
  char buff[10];
  snprintf(buff, sizeof(buff), "%.2f", weight);
  spr.setTextDatum(MC_DATUM); // Center text both horizontally and vertically
  spr.drawString(buff, circleX, textY); // Draw weight text with new y position

  // Push the sprite to the center of the screen
  int spriteX = (240 - spriteWidth) / 2; // Adjust for a 240x240 display
  int spriteY = (240 - spriteHeight) / 2;
  spr.pushSprite(spriteX, spriteY);
}