Uploaded February 2020 | Updated September 2026, 2 weeks ago

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Quick numeric display tutorial
- for nice digits I used 13x20 pixel font with 2x scaling in Y axis (so 13x40 pixels are rendered, even 16x40 with spacing)
- regular bitmap fonts are very slow to render pixel by pixel (350ms in this example)
- however, what "slow" really means can be checked by trying other ST7789 libraries :)
- addeed special OPTIMIZE_BIG_FONTS mode which speeds up rendering of big bitmap fonts about 25%
- RRE fonts encoded in vertical mode give the best results (about 100ms)
- regular RRE fonts (rendered using rectangles) are the fastest and use less memory but flickering can be visible due to every character full background clearing before rendering
- all static data should be drawn only once for the best performance
- even on slow Arduino and high resolution ST7789 final results with RRE fonts are pretty promising, achieved 10 fps refresh rate for 5 big numeric fields using nice digits

The code on my GitHub:
github.com/cbm80amiga/Arduino_ST7789_Fast/tree/master/examples/ST7789_Numeric_display

If you find it useful and you want to buy me a coffee or a beer:
paypal.me/cbm80amiga