Commit e3e6c970 authored by natalie's avatar natalie 💜

Merge branch 'make-readme' into 'master'

add readme

See merge request !1
parents 5d40d8bb b8e7fef2
![](https://git.agiri.ninja/natalie/badapple_gu20x8/uploads/4c215fadc9addb0b7a461cafabb03d5d/badapple.png)
## Overview
This is the famous Touhou Bad Apple!! PV running on a Noritake itron GU20X8-301 color VFD module and an Arduino Mega. An SD card stores 30 FPS video and 16 kHz PCM audio. With a slight modification to its connector shell, the VFD module plugs directly onto the large header on the Mega board, with only a few extra wires needed to provide power and audio output.
## Design
The VFD module is a 20x8 matrix of pairs of blue and red subpixels. I treat the display as being 16 pixels high and divide the blue and red subpixels between even and odd lines of video, which gives a bit more detail than you'd normally get from an 8-pixel high display. Video ends up being displayed in a 2:1 aspect ratio block in the center of the display - it's not exactly 4:3 but it's close enough, easy to convert, and fast!
The Arduino Mega was chosen for this project because the VFD module can be plugged directly onto the large pinheader (a slight modification to the VFD's connector shell is required). 8K of RAM is enough for video and audio buffers and it's fast enough to handle 30 FPS video and 16 kHz PCM audio. Higher audio rates may be achieved through using ADPCM compression or code optimization - it was a bit hairy at 24 kHz so I brought it back down to 16, although I didn't test if the bottleneck is CPU time or SD card read speed.
## Build instructions
Available on Hackaday.io: https://hackaday.io/project/164433/instructions
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