Jens, The horizontal line timing is incorrect. This is why the image is diagonal. The numbers that you provided do not specify the horizontal line total time or frequency. The monitor requires 52 microseconds or 19.2 kHz. You need to find a way to specify this, perhaps it is the character count or pixel count and the pixel frequency.
On Sun, Feb 20, 2022, 6:26 PM jb-electronics <[email protected]> wrote: > Dear all, > > Apologies for the off topic question, but I know there are some CRT > experts in our group and I have been banging my head on this one for a > while. > > I picked up a cute 6" monochrome CRT module which accepts TTL video. This > is the timing chart: > > > My goal is to run this thing using the DPI module of the Raspberry Pi. But > for all of that to work I have to specify certain parameters and pass them > along to the DPI module, and here is what I read off the sheet: > > - h sync: 4.615 us > - h front porch: 2.637 us > - h back porch: 2.637 us > - v sync: 0.208 ms > - v front porch: 0.209 ms > - v back porch: 2.917 ms > - active lines: 256 > > I have verified that at least the vertical signal timing is implemented > correctly, my scope is a tad too slow to resolve the horizontal timing. But > there appears only gibberish on the screen, highly distorted text. Here is > how it looks like: http://jb-electronics.de/tmp/screen01.jpg > > And this is what it should be (composite video output on my Apple IIc > monitor) for the same "scene": http://jb-electronics.de/tmp/screen02.jpg > > Can somebody tell me if I am on the right track here, or if there is a > fundamental mistake somewhere in the numbers I read off? Your help is very > much appreciated. > > Best wishes > Jens > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/5a549b7b-127f-42c3-3dde-4973892d9780%40jb-electronics.de > <https://groups.google.com/d/msgid/neonixie-l/5a549b7b-127f-42c3-3dde-4973892d9780%40jb-electronics.de?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAPbqtvcOPLtvrsz7n7P3Q0J6MZagx-eBJ5624%2BfWRr5tVngFGg%40mail.gmail.com.
