VGA_HiRes_Text

bifferos

I've tried the standard vgatest2.spin program with vga.spin driver for the demo board, and that seemed to work ok on my strip-boarded Propeller setup, however when I try the HiRes driver I get the error in the subject.

I've tried a few combinations of crystal - 12MHz with 8x multiplier, 20MHz with 4x multipler - sometimes when I just unplug the crystal I get a picture, but really messed up. I don't have a 5MHz crystal, and I'm just wondering if there is something timing-critical about this driver that requires a certain crystal-multiplier combination.

The monitor is 1280x1024 and is supposed to do 30-83KHz / 56-75Hz. It's showing 56.8KHz / 91Hz when running the GUI demo from Allen Marincak. Is it just time I got a new monitor or what? [noparse];)[/noparse].

I notice the file VGA_HiRes_Text.spin has some parameters for the different resolutions at the start, but is there some way I can calculate a set of parameters for a reduced vertical refresh frequency without understanding all the gory details of VGA video signal generation?

Much appreciate any advice you can offer!

Biff.

Rayman

I think those crystals are outside the range where you can use the "multiplier"...

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

Ariba

The crystal should be in the range 4 MHz..10 MHz, a 12 MHz may work also, but at 20MHz the PLL will not lock.

The vga.spin calculates the timing from the passed parameters and the clock frequency. The HiRes driver expects a 80 MHz clock.
You can maybe play with the constant pr (pixelrate) to adapt it to other frequencies, but I never tried this.

Andy