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Home Forums Raspberry Pi+Classic CRT — #7 Raspberry Pi+Classic CRT — #7
Post #7 by Bunsen
Source ForumRaspberry Pi+Classic CRT — #7
CategoryHardware
Post DateMon, 4 Mar 2013 - 16:59
Original URLhttps://68kmla.org/bb/threads/raspberry-pi-classic-crt.27433/
Post
Hmmmm so...

Given that eviltim has shown us how to force a TTL monitor to display analog levels, by hijacking the gain pot:

modify.png.160c700e0166996080cd634a113e5fb9.png


... and given that many of these cheap ARM sticks have at least one analog and/or PWM output pin, mayyyyybe with a bit of tweaking of sprite's GPU, you could get greyscale.

[does math]

512 x 342 x 60Hz = 10506240 = just over 10MHz (plus some over for blanking intervals &c)

Getting that kind of speed out of the DAC/PWM on a cheap micro is unlikely, though possibly worth investigating - remembering of course, that it also multiplies your data handling requirements by whatever bit depth you choose (ie, 8 bit greyscale = 8 times as much data)

You could, in theory, use digital pins and an R2R ladder - ie, each pin addresses one bit of your greyscale level, in parallel.

I wonder ... the R-Pi has GPIO pins itself.

/chinscratching and hmmm

mp.ls