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Comment by jsheard | Hacker News Reader

I've been looking into graphics on MCUs and was disappointed to learn that the little "NeoChrom" GPU they're putting on newer STM32 parts is completely undocumented. Historically they have been good about not putting black boxes in their chips, but I guess it's probably an IP block they've licensed from a third party.

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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/

You can do something similar on STM32 parts that have an LCD controller, which can be abused to drive a VGA DAC or a DVI encoder chip. The LCD controller at least is fully documented, but many of their parts pair that with a small GPU, which would be an advantage over the GPU-less RP2040... if there were any public documentation at all for the GPU :(

I used "composite" (actually monochrome) video output software someone wrote on the RP2040 for an optional feature on the PhobGCC custom gamecube controller motherboard to allow easy calibration, configuration, and high-frequency input recording and graphing.

Pictures of the output here: https://github.com/PhobGCC/PhobGCC-doc/blob/main/For_Users/P...

That sucks. There are other MCUs with 2D graphics peripherals, eg the NXP i.MX line.

Agreed. It is so, so, so very disappointing. I was deeply surprised (in a non-pleasant way) when I first opened up a Reference Manual for one of those chips and saw that the GPU chapter was, like, four pages. :(

On the ST forum the company clearly said that they will only release to some selected partners. That's sad.

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