picodvi VS Arduino-Teensy-Codec-lib

The RP2040 is a great MCU for playing with graphics as it can bit bang VGA and DVI/HDMI. There's some info on the DVI here: https://github.com/Wren6991/PicoDVI

I wrote a couple of articles on how to do bit banged VGA on the RP2040 from scratch: https://gregchadwick.co.uk/blog/playing-with-the-pico-pt5/ and https://gregchadwick.co.uk/blog/playing-with-the-pico-pt6/ plus an intro to PIO https://gregchadwick.co.uk/blog/playing-with-the-pico-pt4/

A few years back someone was bit banging DVI and 720p 30fps video straight off the RP2040 GPIO pins with just inline resistors between not and the HDMI cable.

https://github.com/Wren6991/PicoDVI

I have the Adafruit DVI board and have been hacking on it some. It's more fun than should be allowed.

There's a project to get this running using Rust[1]. Currently it outputs the blue channel with sync, but has trouble with the other two channels. I don't have a hardware lab with scope, logic analyzer, etc., so it's not easy for me to debug.

In the meantime, I've been doing some experiments in the C codebase as well[2], mostly in the direction of proportionally spaced bitmap text, using the fonts in the X11 distribution.

[1]: https://github.com/DusterTheFirst/pico-dvi-rs

[2]: https://github.com/Wren6991/PicoDVI/pull/48

There is even bit-banged DVI library for pico.

Apparently, there is a digital video output project for the RP2040 already out there [0]! As for why digital video is more rare, it is because the common digital video formats are higher bandwidth and require higher signal integrity.

[0] https://github.com/Wren6991/PicoDVI

I have seen Micro controllers bit bang HDMI https://github.com/Wren6991/picodvi

Its a great chip all around. 133Mhz Dualcore M0+ and it has 5 programmable state machines. With those it punches way above its weight. Here is a very interesting dvi project for the pico

FWIW, it's possible to bit-bang DVI at 640x480 on the 2040. Takes about half of the available resources:

https://github.com/Wren6991/PicoDVI

The RP2040 (as used by the Raspberry Pi Pico) can generate some impressive video thanks to its PIO. E.g. Luke Wren's work giving DVI output https://github.com/Wren6991/picodvi and the scanvideo library: https://github.com/raspberrypi/pico-playground

I did a write up going over how to generate VGA video from scratch to produce some SNES like graphics:

https://gregchadwick.co.uk/blog/playing-with-the-pico-pt4/

> HDMI is a 10Gbps port.

> The PIO ports discussed here are on the order of 100kHz

PIO runs at the system clock, 125 MHz by default, overclocks of over 400 MHz have been reported stable. A single PIO can clock out 32 bits every cycle (with a DMA and a memory system that can feed this), giving you a total of 4 Gbps.

Running at full throttle like that, especially for a decent length of time is tricky if you want to actually do anything other than blast out bits but 16 or 8 bits per cycle is a lot more straight forward, so 2 or 1 Gbps.

DVI output has already been demonstrated, running two displays at 480p: https://github.com/Wren6991/picodvi

The DVI is maybe more of a party trick than something you'd do in production hardware but it does demonstrate how capable the PIO can be. You could happily implement the same concept in a more performant device and reach 10 Gbps or more in a reasonable way.

Someone has implemented mp3 decoding on a teensy in software only. https://github.com/FrankBoesing/Arduino-Teensy-Codec-lib I think that one has an FPU though...