The array name in your header file is different. Fix: Open Font6x14.h and look for the actual variable name (e.g., font6x14 , ascii6x14 , FONT_6X14 ).
As you can see, 6x14 hits a sweet spot between width efficiency and height for descenders. Font 6x14.h Library Download
After download, check the file begins with #ifndef FONT6X14_H and contains 95 character definitions. Expected file size: ~1.5–2 KB. The array name in your header file is different
Search for the file on GitHub under common display library repositories such as: Look for u8g2_font_6x14_tf . Adafruit_GFX: Often found in the "Fonts" subfolder. FONT_6X14 ). As you can see