Egregoros

@sun What happens between GPIO14 and the VGA RGB pins isn’t perfectly clear. I would expect stepping of some sort to split a single pin into three, if not something that results in a really rudimentary fourier transform

@sun goddamnit sorry my fault, I missed the part where you said black-and-white.

@vii yeah completely passive conversion to all three channels

@sun yeah that checks out to me

@Soy_Magnus thanks, I barely know what I am doing and a unsure about everything.

@sun no worries diagrams suck and are confusing lol

@sun Have you worked out how much current you'll be sinking on those three pins you're driving via GPIO 14?

It might be too much for a single GPIO

@sun whenever i have to make up a basic circuit, https://wokwi.com/projects/new/pi-pico really helps, because you can simulate the entire thing quite well and be left with something you could inspect after the fact and version

could make a whole custom vga display in it https://docs.wokwi.com/chips-api/getting-started

@troonigger I can reduce the GPIO output impedance by setting the drive strength to 8mA on the pin, then when it's split into three, the voltage is almost exactly what analog VGA expects.

@sun
Are you connecting to an old vga monitor?

@tobias no, I just only needed a black and white picture and wanted to reduce how many gpio pins I was using and reduce build complexity.

@sun The diagram is okay but I cannot imagine the CPU on Pi being able to do much when not banging (during the frame blank essentially). Do modern Pis have several cores?

@sun
ok. Look at CGA monochrome mode, which has 2 resolutions.

@sun it was more whether a single GPIO could source enough current to drive the three VGA pins, they're quite low impedance. Your circuit won't go boom, so it'll be interesting to know if it works. I'm guessing the image will be dark and glitchy.

@zaitcev yeah two cores and one is only for the video

@troonigger yeah i don't really know what i'm doing

@sun just try it, if it looks like crap then use three pins. half the fun is trying stuff out.