How to avoid text flicker ?

DrWino

I am writing text to the same location with updated values. I get the text superimposed on the old text. i use a space, the reset the setCursor, then write the new text. But I get flicker - How to avoid this ? Also if you make a filled rectangle and then write text on it - the whole thing flickers like mad.

Sergey_Urusov

Just save previous displayed value in global variable, before display compare with saved, and display only if they differs.

reaper7

this is a good option as @Sergey_Urusov wrote,
instead rectangle you can also overwrite old value with inverted color
something like this:

#include <M5Stack.h>

void setup() {

  M5.begin();

  M5.Lcd.fillScreen(BLACK);
  M5.Lcd.setTextSize(7);

}

void loop(){
  static int rndold = -1;

  int rnd = random(0, 100);

  if (rnd != rndold) {
    //overwrite old value with inverted color
    M5.Lcd.setCursor(40, 40);
    M5.Lcd.setTextColor(BLACK);
    M5.Lcd.printf("%02d", rndold);
    //write new value
    M5.Lcd.setCursor(40, 40);
    M5.Lcd.setTextColor(WHITE);
    M5.Lcd.printf("%02d", rnd);
    rndold = rnd;
    delay(250);
  }
  
}

daslolo

You can try PrintToSprite in the TFT_eSPI library. https://github.com/Bodmer/TFT_eSPI/issues/116

daslolo

Here is the solution. https://github.com/Bodmer/TFT_eSPI/tree/master/examples/Sprite/Sprite_scroll

Thanks to @Calin