Custom Glyphs

Besides the supported characters, you can create your own custom characters(glyphs), like smileys or heart symbols. The module includes 64 bytes of Character Generator RAM (CGRAM), allowing up to 8 custom glyphs.

The controller provides 64 bytes of Character Generator RAM (CGRAM). Each custom glyph occupies 8 bytes, so you can store up to 8 custom glyphs at a time.

Each glyph is an 8x8 grid, where each row is represented by a single 8-bit value (u8). This makes it 8 bytes per glyph (8 rows × 1 byte per row). That is why, with a total of 64 bytes, you can only store up to 8 custom glyphs (8 glyphs × 8 bytes = 64 bytes).

Note: If you recall, in our LCD module, each character is represented as a 5x8 grid. But wait, didn’t we say we need an 8x8 grid for the characters? Yes, that’s correct-we need 8 x 8 (8 bytes) memory, but we only use 5 bits in each row. The 3 high-order bits in each row are left as zeros.