💾 Archived View for librehacker.com › gemlog › tech › 20220504-0.gmi captured on 2024-05-26 at 15:28:53. Gemini links have been rewritten to link to archived content

-=-=-=-=-=-=-

Forth LCD Character Demo

I'm working on little demo programs for the Mecrisp/RP2040 LCD display driver I've been coding. I just added one which displays all 256 character patterns available in memory. The characters are displayed on four pages. Here is a picture of the second page, displaying characters 0x40-7F:

LCD display character demo, page 2

And here is a picture of the fourth page, displaying characters 0xC0-FF:

LCD display character demo, page 4

The characters you see depend on the character patterns that were burnt into the ROM of the unit you bought.

I was wondering also about the possibility of doing bitmap graphics on the display. It turns out that it is possible for the user to store their own character patterns in CGRAM, and the first eight character codes refer to these patterns. Therefore, you can define your own drawing characters, and so simulate bitmap drawing in the manner of historic 8-bit personal computers. However, since you only get eight character codes to work with, that limits you to a rather blockly resolution of either block pixels or grayscale shades. I was thinking to put together a demo for that idea in the coming days.

Christopher Howard