353 DOTTEE VGA demo (TTGF26a)
353 : DOTTEE VGA demo (TTGF26a)
- Author: algofoogle (Anton Maurovic)
- Description: DOTTEE: Pretty little 1-tile Tiny Tapeout ASIC demo (TTGF26a version)
- GitHub repository
- Open in 3D viewer
- Open in VGA Playground
- Clock: 25175000 Hz
How it works
DOTTEE is a Verilog/ASIC demoscene project, originally submitted to the Tiny Tapeout ttsky26a Demoscene Competition in the 1-tile category. This is an enhanced version, resubmitted to the TTGF26a shuttle for fun.
This demo races the beam to create a VGA 640x480 60fps output, while generating some music using a 1-bit sigma-delta DAC. It loops after 4096 frames (about 68 seconds). The main theme of the demo is: dots (well, circles). It uses a rough approximation of squared Euclidean distance for per-pixel rendering of an array of multi-coloured circles of various radii. It also uses a Bresenham-like circle calculation to slowly compute the edges of two larger circles (during HBLANK) which are used to construct the "DOTTEE" logo (where the 'TT' in that is a rendition of the Tiny Tapeout logo).
This demo also synthesises some music using a couple of voices (i.e. phase accumulators) that generate triangle waves (but also mangle them a bit to create other effects). New to this TTGF26a version too is a simple noise generator hack (based on vertical line index and some other bit-mangling) that adds simple percussive sounds. Audio output is by converting 6-bit audio samples (at the HSYNC frequency of about 31.5kHz) to 1-bit PDM (at clk frequency; i.e. about 25MHz) using a sigma-delta DAC.
How to test
Keep ui_in bits all set to 0. Attach a Tiny VGA PMOD adapter to the output (uo_out) port and a Tiny Audio PMOD adapter to the bidirectional (uio) port, supply a ~25MHz clock, and reset the design. Watch and listen!
ui_in also gets ORed with the upper 8 bits of the 12-bit frame counter (from which all stages and timing of the demo are derived), so it can be used for debugging by jumping ahead in multiples of 16 frames.
External hardware
- Tiny VGA PMOD for driving a VGA monitor.
- TT Audio PMOD for mono sound.
Attribution
By all means feel free to build upon this project with your own work, but please acknowledge this project and credit me (Anton Maurovic, https://github.com/algofoogle, https://foogle.com/anton) as the original author.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | debug[0] | R1 | |
| 1 | debug[1] | G1 | |
| 2 | debug[2] | B1 | |
| 3 | debug[3] | VSync | |
| 4 | debug[4] | R0 | |
| 5 | debug[5] | G0 | |
| 6 | debug[6] | B0 | |
| 7 | debug[7] | HSync | audio_out |