644 VGA Nyan Cat
644 : VGA Nyan Cat
- Author: Andy Sloane
- Description: Displays the classic nyan.cat animation
- GitHub repository
- Clock: 25175000 Hz
VGA nyan cat
How it works
Outputs nyancat on VGA with music!
Colors and animation are all from the original nyan.cat site, using a 2x2 Bayer dithering matrix which inverts on alternate frames for better color rendition on the Tiny VGA Pmod.
Sound is generated from a MIDI file, split into melody and bass parts. Melody and bass are each square waves mixed with a simple exponential decay envelope, which is then fed to a low-pass filter and then a sigma-delta DAC.
This was designed to fit into 1 tile, and it almost did -- the cells take up about 93% of 1 tile, but detailed routing doesn't finish. With the deadline approaching I was forced to grow it to 1x2, so I threw in a little easter egg.
How to test
Set clock to 25.175MHz or thereabouts, give reset pulse, and enjoy
External hardware
TinyVGA Pmod for video on o[7:0].
1-bit sound on io[7], compatible with Tiny Tapeout Audio Pmod, or any basic ~20kHz RC filter on io7 to an amplifier will work.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | R1 | ||
| 1 | G1 | ||
| 2 | B1 | ||
| 3 | VSync | ||
| 4 | R0 | ||
| 5 | G0 | ||
| 6 | B0 | ||
| 7 | HSync | AudioPWM |