mcufriend_kbv and adafruit_GFX text re-printing without flicker?

I want to rapidly update some large text on a 320x200 TFT.

At the moment I am over printing in black to clear the old text before printing the new data. This is still showing a lot of flicker, even with the improved data bus wiring on a Mega.

Any other ways to cut down flicker? I guess I want faster printing...

To print 4 digits in 24pt font, in black, the print the new value in white is taking about 70-90ms.

All the text printing is done with Adafruit_GFX plotting individual pixels with drawPixel().
This is inherently SLOW.

If you want it to look better, you paint small sections of background and plot the new letters a few at a time.

Yes, it is much faster to draw background and letters in hardware. The library does not provide the specific hardware method. I can show you how to write your own helper function. Or a Super class.

Adafruit FreeFonts only print “transparently”. If you use the System 5x7 font in 3X size you can draw in “rubout” mode but it looks very blocky.

What font are you using?

David.

david_prentice:
All the text printing is done with Adafruit_GFX plotting individual pixels with drawPixel().
This is inherently SLOW.

If you want it to look better, you paint small sections of background and plot the new letters a few at a time.

Yes, it is much faster to draw background and letters in hardware. The library does not provide the specific hardware method. I can show you how to write your own helper function. Or a Super class.

Adafruit FreeFonts only print "transparently". If you use the System 5x7 font in 3X size you can draw in "rubout" mode but it looks very blocky.

What font are you using?

David.

Hi David,

Yes I am using FreeFonts as I wanted cleaner text. FreeSansBold24pt7b. The system fonts look terrible at any of the larger sizes.

Richard.